Instant Death Radius

""Oh, and this melee class is working just super. I love getting wasted before dealing a single hit in.""

- Leo of VG Cats, see picture.

Sometimes the best way to make a powerful boss character is to make sure that they have really, really good melee/short-ranged attacks. So good, in fact, that it's just about impossible for a player character to get anywhere near this boss without ending up dead in a matter of seconds. This is because the boss in question is contained in an Instant Death Radius -- an attack range in which they can easily kill you, but in which you are just about incapable of even getting close enough to touch them, let alone denting them.

Done well, this kind of enemy can force a player into using a very clear kind of strategy -- keep as far away from it as possible and use ranged attacks, or wait for an opening when it can't attack and strike quickly. But other times this kind of enemy can be incredibly aggravating when there's major character customization involved. Sure, you want to play a melee class, but guess what -- the monster's attack radius is much larger than yours, and their attacks are substantially stronger. Level up as you might, mano a mano combat is going to result in your death no matter how many Critical Hits you land (generally zero -- one if you're lucky). A Puzzle Boss may invoke this trope as a way of making it perfectly clear to the player that they're not going to beat it by conventional means, as will the Tactical Suicide Boss to ensure that the player waits for their opening. A Short Range Shotgun may cause this effect.

Tabletop Games

 * Dungeons & Dragons 3rd Edition was lousy with this, as monsters with reach (such as any monster that was larger than you) could lay serious hurt on you with an Attack of Opportunity if you got within its radius, and unless the monster was using a reach weapon, it could threaten every square within its radius, meaning you could not charge or otherwise get close without sucking up an Attack of Opportunity and taking some heinous damage (because any melee monster worth its salt invariably has very high Strength, and high Strength = high attack bonus = high damage). A caster or archer could just hang back and blast them at range, but if you were a fighter or other class whose primary focus was on melee and wielding the weapons you would normally expect such characters to wield (swords, spears, axes, hammers and other weapons with normal reach), you could pretty much forget about actually doing any damage or contributing to the fight in any way other than being a "meat shield" for the others. Little wonder that the five-foot-step rule, which is called "shifting" in 4th Edition, was clarified in 3.5.
 * It got much worse if the enemies were good at tripping or grappling; one Huge monster in the Monster Manual 4 has an anti-magic grab, preferred subterranean environs, and moves with a faster climb speed than many characters of the appropriate level could run. Fortunately (or unfortunately for the DM) Attack of Opportunity optimized character builds can invert this trope entirely. Radical Taoist developed a number of builds on the Wizards of the Coast forums (the best known of which was called Lester the Molester) that could not be approached without provoking tons of AoOs; this character would attack a foe if that foe attacked him, attacked a nearby ally, or moved -- hell, even if they did nothing at all.
 * The main thing though isn't the AoOs, but the full attack that follows. You can expect even the half-decent melee enemies to utterly annihilate you later on accordingly or at least beat you to within an inch of your life before you get another turn. Not sometimes, but every single turn. Dragons are infamous for this, as the higher age categories get six or more attacks per round. And the only way to stand up to regular melee enemies in close combat is to either be an Evasion Tank (see Linear Warriors Quadratic Wizards) or just be heavily optimized...in effect, stuff that would normally be a Game Breaker is required for basic competency.
 * Attack of Opportunity! Attack of Opportunity!
 * One of third edition's supplements introduced a monster-only feat "Large and In Charge" which allowed them to add knockback to their attack of opportunity against human-sized attackers.
 * In Warhammer 40000, getting in close combat with Khorne Berserkers, Genestealers, and Grey Knight Terminators is simply a death wish. One troper who uses Grey Knights had a game in which a Grey Knight Hero and 5 Terminators single handedly chopped up an Eldar Avatar, Wraithlord, a Warlock and his buddies (through shooting), and an entire 20 man Guardian team in the same game in 5 different close combats.
 * It is an exceedingly bad idea to let a Carnifex near your tanks. not even your prized Monolith will last the assault phase...
 * Another oft-noted example is the Leman Russ Demolishor. With a 24" Instant Death Radius for it's Demolishor Cannon, most players give one a wide berth. Unfortunately, a Leman Russ also has at least one other weapon, so staying away from the big gun doesn't quite mean you're safe.
 * Only a foolish player fails to give a wide berth to units like Kharn The Betrayer (His Instant Death Radius extends to allies in range of his axe), Ghazghkull (Sure he's a Mighty Glacier, but watch him and a few nobs assaulting anything that isn't comprised of 30+ Models. Not even the two most heavily armoured vehicles will last a single assault turn just by going on the averages of dice rolls) and the notorious Nob Biker List (Despite no longer being the monster it once was, it was for quite a while the Fuck You list for Ork players in the Tournment scene; boasting a single centerpiece unit which simply refused to die, was a scoring unit, moved quite fast and destroyed anything within its 18" range of death).
 * The Eldar Farseer's Mind War power is another example, it pretty much instant kills a single model within 18" unless they've got Ld 10 and a lot of Wounds (and sometimes even then) if you roll well. Also useful for 'declawing' a unit by removing it's heavy weapon trooper or Power Fist-wielding squad leader.
 * The Eldar Revenant can unleash four strength Destroyer Large Blast templates in a single turn against up to two targets 60" away. Good luck surviving that, Space Marines!
 * Several classic Battle Tech designs (Hunchback, Victor, Demolisher, Atlas, you name them) have a reputation for this. The thing they have in common is the AC/20 -- the biggest autocannon in the game, short ranged but able to inflict potentially crippling damage all to a single location in one shot. As a result, most units much prefer to stay outside its nine-hex 'bubble of doom'.
 * This also applies to the Gauss Rifle family and Clan ER-PPC weapons, both of which may hit only 75% as hard as the AC/20, but reach out to a range in excess of 20 hexes while being capable of taking off a 'Mech's head with a single shot.
 * Call of Cthulhu quite deliberately gives this capability to its upper-tier Eldritch Abominations to discourage Munchkins from fighting them. The titular Cthulhu has an unblockable, undodgeable One Hit Polykill at close range, and the power levels actually go up from there.

Video Games

 * Ekinard from Zenonia 3 spews toxic clouds that follow you around effectively making it impossible to hit him EVEN WITH THE RANGED CLASSES. Literally the only way to beat him is with hit-and-run Cherry Tapping.
 * This is exactly what happens when you get too close to a really good Zangief player (or a really cheap computer-controlled Zangief) in Street Fighter. He can't "instantly" KO you, but there's a psychological intimidation factor involved: You're basically fighting an Implacable Man who will punish every little mistake with a Spinning Pile Driver or its much more brutal version, the Final Atomic Buster. Even at a distance you're still not safe as he can close the gap with his running powerbomb.
 * Jumping's not safe either as he'll catch you with the Aerial Russian Slam from Alpha 2&3 and the more painful Siberian Blizzard from SSFIV.
 * In Alpha Protocol a player can specialize his character in stealth and melee attacks (and since there aren't very many stealth games out there, a lot of fans of this playstyle bought Alpha Protocol), and then run into the game's bosses that can't be snuck up on, and can kill you in a few hits while they can take 50 shotgun shells to the face. There isn't really a way to beat these bosses unless you invested in some guns. The problem is that these bosses only pop up after the first act, so you might have invested several hours in character that can't get past these bosses.
 * There is a skill called Point Blank Shot that allows you to finish a melee combo with a pistol shot For Massive Damage. It's extremely powerful against bosses, but requires you to invest a lot of skill points in your melee ability (it's the last skill you unlock), meaning you're either specializing in it early to the detriment of your other skills, or you're not going to have it for the first few bosses.
 * Diablo II is loaded with enemies like this, the most notable examples being Diablo and Duriel. Inverted in the case of Mephisto, who has deadly ranged attacks, but will only use wimpy melee attacks at close quarters.
 * Actually, standing up to Diablo is the best way to beat him with a weak character. His lightning hose has a gap right next to him so he'll literally shoot it past you, he won't cast bone prison when you're next to him, his cold melee and firestorm attacks can be dodged since they have big backswings and don't follow you, and his flaming circle attack always hits you anyway. Duriel's radius of death is about the same size as his room, so it doesn't really count. And Mephisto's best fought from across the chasm with a weak character - he doesn't exclusively melee when you're next to him, and his melee is a bit too much for a weak character anyway.
 * Duriel is also easier to survive if either a player or a minion is next to him since that prevents him from using his charge attack, which stuns its target.
 * Melee characters are widely regarded as not viable unless you have the best items in the game. For instance, there are a handful of bugged monsters that are virtually impossible to kill in melee before they annihilate you from extreme range. And one monster type used to cast a curse on you that caused you to pretty much kill yourself when you hit anything in melee. It could cast this while you were in the middle of a whirlwind or zeal hit sequence resulting in an unavoidable instant death.
 * The somewhat popular Diablo II: Lord of Destruction mod "Eastern Sun" nerfed the monster version of the spell in question (Iron Maiden, a Necromancer Curse), thus making it possible to actually complete Act IV with a melee character.
 * The "Median XL" mod has a literal instant death radius in the form of the "witch" monster: a motionless ghost that announces its presence with an eerie song. It does nothing, but when you get close enough she notices you and laughs; if you do not immediately get out of range, she teleports at you and kills you with an unresistable and unblockable attack that deals 50,000 damage per frame.
 * Pretty much every boss in Champions of Norrath is this. Doesn't matter if your class is supposed to be melee only, you don't go near these things. The sequel's bosses tend to be a bit less dangerous in melee, although there's still a few that getting close to will get you killed in a hurry.
 * Many Forgotten Realms games, but the Baldurs Gate series in particular uses this trope. Sometimes the use of this trope is forgivable, as when you confront a powerful demon. Other times it's just somebody's random bodyguard who's so good at creaming that he causes the near-instantaneous Berserk "spell" to fail.
 * Baldurs Gate II inverts this by eventually giving the player access to a character who can transform into a creature with an Instant Death Radius.
 * Also, beholders are a lot less scary once you get all up in their business.
 * According to the official D&D Monster Manual, beholders are well aware of that fact.
 * Baldurs Gate Dark Alliance however has this trope in full effect on harder difficulties. The melee character gets oneshot by almost anything before he can close range and swing his weapon.
 * Rancors in pretty much any Star Wars game will wipe out player characters in a single hit if they get too close. In the games where they can actually be killed, namely Knights of the Old Republic, you'll want to do so with lasers and mines.
 * Used a couple times in The Legend of Zelda, usually as an indicator that the enemy or boss needs to be stunned before it can be attacked. The purest example would be Gyorg, the giant fish boss in Majora's Mask. Attempting to take the fight to him in the water will put you in range of his unavoidable (and highly damaging) bites.
 * Ghirahim from Skyward Sword can quickly become this if you don't figure out how to play quickly or are starting to panic and start randomly swinging. It doesn't help that he's the first boss either (though at this point, if you're doing badly enough, he'll start giving you pointers on how to fight him).
 * Skyward Sword also gave us The Imprisoned. To defeat it you must chop off its toes. This is made difficult by the fact that it shoots out shockwaves from it's feet every time it takes a step. Frustratingly, this is one of the game's recurring boss battles and you don't have any real ranged attacks or ways to stun it for the first few times.
 * In Silent Hill 2, Pyramid Head qualifies as it. He's really hard to shake off once you get grappled. Also, during the first battle, his BFS attacks will kill you in one hit. In the first game, the Split-Head can insta-kill you with its vertical jaws when it Turns Red.
 * Melkor in ToME has such utterly nasty melee attacks that trying to kill him by whacking him with a sword is a losing proposition. In addition, strict melee types are the ones that will be the most inconvenienced by his summoning magic. And we are talking about an optional boss at a point in the game where any character has long ago hit the level cap, so just trying to munchkin it out won't be very effective.
 * The first Code Lyoko DS game tends to rely on you blocking and reflecting shots. Why? Because when you get too close into melee range, the monsters start using unblockable melee attacks. Combine this with an upgrade/revive system that can make the game Unwinnable, and it becomes apparent that Lyoko has become Goddamn Bat Country.
 * God forbid you choose to make a melee-specialised character in Phantasy Star Universe. The bosses seem hell-bent on ruining any character that even remotely comes close to melee range.
 * This goes for just about any 3D Phantasy Star game. One example appears in Zer0; the first boss, Diablo Octopus, sits in the water in the middle of the stage, away from melee reach, with the only way to damage it with swords is by going to the damage-giving tentacles. Not only that, but he has a Spin Attack that does three sets of damage to anyone close enough, and by close enough, we mean anyone that isn't up against the borders of the stage.
 * While many monsters can floor you with a hit or two in Final Fantasy XI, boss-level Monk monsters can use Hundred Fists, an ability that allows non-stop, no-delay attacks that pretty much insta-kill anyone that has hate. Normally only Paladins have a chance to not die, provided that they have the Sentinel ability at the ready, or Invincible if Sentinel is still on a timer... that is, if said Paladin actually uses Invincible! Thieves could also survive with Perfect Dodge, but a Thief rarely tanks outside of soloing, if ever, so you might not see it as much.
 * More literally is the final boss of the DLC story pack, A Crystaline Prophecy. The final boss is a stationary crystal. It has some hard hitting aoe spells, but nothing players haven't tangled with before. The problem? It also has an aoe attack centered on itself that charms all party members in range and turn them into a cute little plant monster (in look). Oh, and it can use Draw In to drag the current target of its ire right into proximity. Melee players have been screwed in trying to find parties for this fight, which is why it pays to have many spellcaster friends.
 * Charybdis is a giant octopus who can multi attack up to six times per round. The only way to fight him solo is to either load up a ridiculous amount of evasion gear on a Thief so he can't hit you or to slow his movement speed as a Red Mage and run around the room until your damage over time spells slowly whittle down his hp over the course of several hours.
 * Odin's Astral Flow Zantetsuken is an Instant Death Radius, it will kill any player close by who is not "showing reverence". (AKA, resting. And then it still causes a fair amount of damage.) It actually works for players with Odin, but only a chance of it instantly KO'ing every mob in the vicinity.
 * Several Notorious Monsters have "aura" effects, status ailments that will apply to players if they are within range. While some of them are strictly annoying, some of them can kill you, such as Poison, Bio and Doom. Yes, Square loves killing you so much that there are mobs that can kill you even if they aren't thinking about you.
 * Solvaring from Quest 64 attacks with a powerful beam of magma if you stay at a distance. If you get in close, though, he attacks with an even more powerful and unavoidable rock spike attack.
 * Nearly every boss in the game has a stupidly devastating melee-range spell. Shilf is about the only one that getting close is a remotely good idea.
 * Used in World of Warcraft, but generally only on a temporary basis. Many of them are one-shot spells that are technically survivable, but the healers won't like you.
 * Frequently found on at least one of the members of each Quirky Miniboss Squad (Maulgar, Kaelthas, Illidari Council).
 * The Shade of Aran will pull casters in to melee range shortly before casting his instant death radius spell.
 * Demonform Illidan is so dangerous in melee that he's tanked not by a regular tank class but by a warlock, so they can hold aggro without getting near him. (And also because he only deals spell damage in this form, making their armor useless.)
 * The Zombie Chows during the Gluth encounter in Naxxramas. In the Northrend version of the instance, they have 500,000 health points - more than some heroic bosses. They have to be kept in line to avoid them from healing Gluth, but they have a melee attack that applies an armour-reducing debuff. Thus, they're usually kited by ranged attackers with a slowing ability, like frost mages.
 * Yogg-Saron, befitting his status as an Eldritch Abomination, basically has this when players reach his brain. It casts a 20 second cast time spell that turns everyone still in there insane... which is worse than death in the sense that they are turned against the other players and the effect persists through death, making it pointless to use any in-combat means to revive them.
 * Sindragosa pulls the entirety of the group to the centre of her oddly shaped hitbox before beginning to cast a devastating aura attack. It happens quickly enough that players are recommended to turn around while they're flying through the air.
 * Inverted by Loken in the Halls of Lightning; who while possessing a periodically-used lightning-nova attack that can inflict severe pain on lesser-geared characters in a significant radius, also has a pulsing electrical aura that actually does more damage the further away you are from him.
 * Loken is a spiritual successor to Murmur in the Shadow Labyrinth, which had an inverse version of this trope active whenever he wasn't casting his nova attack in the heroic version, meaning that everyone had to stay fairly close to the boss and run away at the right time just outside the circle on the ground that marks the radius. A few other (mostly immobile) bosses had comparable abilities they only used when no one was near them, mostly to prevent players from trying to cheat.
 * Certain outdoors raid bosses will apply "Mark" debuffs against players they kill which will stop the player from fighting them again for a while. This is done to prevent graveyard zerging. The four Nightmare green dragons place a Mark of Nature that puts you to sleep if you approach, the blue dragon Azuregos freezes you into an iceblock if you try, and the Outland Fel Reaver Doomwalker has a Mark of Death. You guess what it does.
 * Several Heroic Bosses in Cataclysm have an Instant Death Radius as part of their fights:
 * Rom'ogg Bonecrusher pulls everyone into Melee Range and spawns an NPC called Chains of Woe that binds everyone to that spot. It must be quickly destroyed before Rom'ogg completes his attack and basically one-shots most players in range.
 * Ozruk has the ability Shatter, which causes a visible radius to appear around him as he lifts a leg. If you do not run out of the radius in time, you pretty much die. To make matters worse, he paralyzes everyone before using it, so you need to have a Damage over Time effect on you in order to escape. Luckily his mechanics do provide such options.
 * Assad has a sort of 'inverse death radius', in that everywhere but a designed safe zone is the death radius every now and then. To complicate matters, he casts Static Cling which you need to jump to avoid.
 * Vanessa Vancleef has an Instant Death Radius right at the end of the fight, where she basically tries to take you down with her by igniting a barrel of Gunpowder. Luckily you have several seconds to run.
 * As a panic button, administrators can spawn avatars that have a literal instant death radius.
 * One word: Whirlwind
 * While playing Dwarf Fortress adventure mode, if you lose stealth within about 10 squares of a giant cave spider, no one will find your body.
 * Crossbow range in Fortress Mode also qualifies. Let's just say that crossbows can potentially punch through all of your internal organs and leave it at that. And they have firing rates akin to machine guns.
 * City of Heroes has quite a few bosses whose melee powers are much more formidable than their ranged attacks. Some even have damage auras, where if you are standing next to them, you'll get hurt, badly, even if you haven't drawn their attention yet. A melee character trying to take on such an enemy is going to be in a world of hurt without some serious support, and that's not even factoring in resistances on the part of the enemy...
 * Such damage auras are also available to the players, so they can invoke this trope on lesser foes. Still, the archvillain versions are seriously amped up in the amount of damage they deal.
 * Most notable is the Envoy of Shadows, an AV of the resident Demonic Invaders who has TWO damaging auras, fire and darkness. I guess it must be what it's like to try and melee a Spines/Dark armor scrapper
 * The Cave Troll enemy Took a Level In Badass in recent Castlevania games and now has an electric attack that spreads an azure ring around him. If you get caught inside it, the ring will stun you at every hit which takes away in the worst cases 90-100 lifepoints every nanosecond. The only way to survive is to heal yourself while still being hit, otherwise you can only hand over your ass to the monster.
 * This was quite a shock to everybody playing Portrait of Ruin who was coming off Dawn of Sorrow. If you say you didn't die on this thing at least once, you are a Goddamned LIAR.
 * The wall-based Guardian necromorph in Dead Space is one of these. Getting within a certain radius of it while it's still alive (well, alive-ish) will instantly decapitate your character.
 * The final boss ofArc the Lad: Twilight of the Spirits. Unless you knew exactly what was coming (and the only way to do so is with a walkthrough) and equipped your melee fighters with all the normally-useless elemental protection you can get, getting in close with him is a deathwish.
 * Many very large enemies in Serious Sam like the huge lava golem, Ugh Zan III or reptiloid highlanders have deadly melee attacks which can kill player almost instantly.
 * Mathematically, if not thematically, inverted with Hakumen and Nu-13 of Blaz Blue. As bosses in a fighting game's Arcade Mode, they have smarter AI than the opponents the player has fought before. This means they seem conscious of the fact that there are ranges at which they can attack, but most characters can't hit them back. Hakumen has a space between "whatever range his opponent can hit at" and "the end of his BFS" where he can attack with impunity. Nu has vicious and unpredictable ranged attacks --for Nu and her Confusion Fu, the Instant Death Radius is the half of the screen farthest from her.
 * On higher difficulties or against a skilled human player, you do not want to get within grab range of Tager.
 * Ragna's Devoured by Darkness Distortion Drive bites off a lot of the enemy's health and gives it to him. Pity about it being so Awesome but Impractical, starting from being limited to grab range and getting worse from there.
 * Then, there is Unlimited Ragna. His Devoured by Darkness is in no way impractical and a 2-hit kill that vastly refills his considerable life bar.
 * Continuum Shift has Unlimited Hazama, who literally has a ring around him that drains your health.
 * It's generally a bad idea to go melee with the stronger enemies in Prototype; hit and run tactics are usually the way to go. This is especially true when fighting Badass Normal Cross. Yes, his missile launcher hurts. But his stun baton is even worse. This is inverted in the case of tanks. Aside from using your own vehicle, the more powerful melee powers such as the Hammerfist or the Blade are the best methods to take out tanks. Especially the . When you face that beast, the goal is to stick to it as closely as possible to keep it from firing. Otherwise, it will kill even a fully upgraded Alex with full health in one or two hits. But it's (mostly) okay, as pretty much all normal infantry that Alex gets close enough to will usually die within seconds, and even the aforementioned Elite Mooks aren't much problem if they're caught alone. Then you get to Groundspike Graveyard and Tendril Barrage Devastators, which can expand the radius somewhat...
 * In Rainbow Six Vegas 1 & 2, if you encounter an enemy at point blank range, you're pretty much dead. Most noticeable when you turn a corner with an enemy hiding right around it. This is probably to discourage rushing your enemies, but it's quite obvious that their accuracy and reflexes make you wonder if these guys actually distinguish friend or foe. Even worse, they become Demonic Spiders when they rush you.
 * Similarly, with most of the games, particular on Elite difficulty, if an enemy sees you, they will more than likely get a near-instant One Hit Kill shot. Even at long range.
 * In Killzone 2 the knife is a One Hit Kill both for you and your enemies.
 * Ace Combat X: Skies of Deception has the Shock Cannon on the Gleipnir  that shows a red flashing circle on the Enemy Detecting Radar when it's ready. If you get into it, say bye-bye. The mission Blitz, as well as Solitaire from 5: The Unsung War, has circles of radar coverage that, while not killing you outright, will cause a mission failure if you wander into them. In 4: Shattered Skies, anyone who made the mistake of getting within 850 feet of Mobius One using a QAAM-equipped plane had effectively received his death sentence. X also has the mission In Pursuit, where "high-performance SAMs" protect a group of jammers from you, flying within their coverage is a death wish.
 * Basically, almost all missions that require you on fly in a ravine would make it perfectly clear that, if you fly over it, it's mission failure, no second chances.
 * In Syphon Filter if you see the flashing "headshot" indicator above your head, you better run for cover ASAP or Your Head Asplode. The snipers never miss. Some bosses will also headshot you if you get too close; one requires you to shoot the lights out so you can nonlethally subdue him.
 * In Duke Nukem 3D, running into any of the end-of-episode bosses will result in you getting crushed to death beneath their feet.
 * Tigrex in Monster Hunter Freedom Unite has a tail whip that trips you and pulls you toward him. If you are close and not in front of him, this is basically all he does. If he hits you with one, he hits you with as many as he wants (i.e. you die).
 * Mobile Bosses in Gundam vs. Series have a death sentence for suits with motion wave guns as their standard arsenal as most of them have Attack Drone units to blindside your suit while their charge attack can knock off three quarters of your health.
 * The Leechgrave in Kingdom Hearts 358 Days Over 2 is like this, forcing the player to kill off the four Tentaclaws to allow the main part to be attacked safely (your death is pretty much guaranteed if you try to go for the main part otherwise, and your attack won't do nearly as much damage either).
 * Vergil from Devil May Cry 3 will start summoning Spiral Swords once you lower him to 2/3 health in Dante Must Die mode. As the name suggests, this creates swords spinning around him that damage and hitstun you. Since you are on DMD, prepare for a world of hurt when he takes advantage of this. Fortunately, they don't last forever.
 * Inverted with Beowulf, however. He's a toughie in close, so you might think that sticking to Dante's guns is the way to go. Well, he's got a nasty, nasty feathers of light attack that he may use when you get Dante too far from him, and then you're in trouble. Big trouble.
 * Team Fortress 2 has the Sentry Guns, and the Engineer getting ready to build said gun can actually see the range of the weapon via a translucent colored sphere with the radius measured out from the barrel. Needless to say, anyone on the opposite team who comes within this range will find themselves on the wrong end of a lead barrage. Though luckily for the other team, attacks to buildings suffer no damage falloff and thus most classes can destroy an unguarded one with ease if they can hit it from outside its range.
 * The Pyro is a blazing deathball within a space of about five meters, and also possesses a rather effective array of melee weapons as well. Any further out however, and nothing in the Pyro's arsenal but secondary weapons will be able to hit you at all.
 * The Heavy basically turns into an Instant Death Radius up to medium range any time the minigun is revved up. At point blank range, anything that has the misfortune to be in front of a Heavy--even another Heavy--will die in less than a second.
 * Every boss in Valkyrie Profile Covenant of the Plume other than the first one can automatically use a special attack at the end of their chain of attacks against you, even if they wouldn't be able to do so had you taken another story path and recruited them. Unless you have a lot of HP or you're using one of the main character's unique abilities, this is for all intents and purposes an automatic knockout. What's worse, if your characters attack en masse and the counter manages to KO one of you without the use of a special, they'll use the special on a second attacking character, typically knocking them out too. Against sword-using bosses like Darius, this means you shouldn't let anyone other than the main character get within reach of the counter, and maybe not even him until you've worn your foe down a bit. Against mages like Liselotte, well, here's hoping you've got at least five revival items on hand. And then there's the final boss of the good path, whose counter targets every character who attacked her and has a chance of stunning anyone who survives it.
 * Ninja Gaiden, Xbox remake, has the Gleaming Blade move and its Ultimate Technique versions. They do a number on normal enemies and can punish even Master Ninja bosses significantly.
 * In one Cortex Command mod, there are robots known as Zombie Bots, which can instantly gib anybody within their claw attack radius.
 * In the Flash Game Amorphous+, the gravity-controlling Void Eater has an attack where it sends out a deadly shockwave, killing anything in the radius. Worse, the radius is larger than your character's BFS swing. You will need to know when the Void Eater will use an attack where it becomes vulnerable, so you don't get turned into Ludicrous Gibs.
 * In Fire Emblem: Path of Radiance, god help you if you leave a character within range of the Black Knight.
 * Ashnard does enough damage to take out most characters in one move, and has a flying movement range of 10! On Hard, he will take any opportunity he can to kill weaker characters.
 * In Valkyria Chronicles, Selvaria's zone extends to anything in her field of vision. Basically, she carries a More Dakka BFG with the accuracy and range of a sniper rifle! Did I mention she has the high ground from the start of the mission, and you have to climb up from the bottom. With her firing on you the whole time. Even worse, some of your units actually start inside her Radius, meaning they'll probably die the moment you attempt to move them. The only way to stay alive is to be completley hidden from view, which is easier said than done seeing as she has the mobility of a Scout. (Being out of view on your turn doesn't necissarily mean you'll be out of view once she finishes moving...)
 * Hellgate London Tormentors have a damage radius that may not be instant, but if multiples overlap it becomes quick enough to be virtually instantaneous. They approach at a slow creep, but terrain and turns can trap a player inside the field.
 * In Just Cause 2, you fight the Russian agent Alexander Mirkov who is armed with an APC-mounted minigun on top of a skyscraper. The fight would be trivial if you could just grapple your way to the top of the vehicle and dispose of him up close, but the area around the APC is full of proximity-triggered explosives that will kill you instantly if you get too close.
 * Space Invaders: Infinity Gene has the "Field" weapon that fires lasers which zap any does that fly within a certain area around your ship. When fully powered up, the field covers about 75% of the screen, meaning that just about anyone that gets anywhere near you is toast.
 * Any goddamn flying enemy in Final Fantasy XII. Especially the Esper in Zertinan Caverns, which is also immune to magic (and raises a Paling around itself at one point). Unless you have a ranged weapon equipped, you will be trounced.
 * That is, until you get the Technick allowing you to attack from a range with any weapon. But that is only available later in the game or by rushing through a high-leveled area and hoping you don't die.
 * In Soldier of Fortune: Payback, enemies do quadruple damage if they shoot you within about 6-10 feet or so, which results in a point-blank shot pretty much resulting in instant death. The last 3 levels ramp up the challenge to Fake Difficulty levels by increasing this Instant Death Radius to about 50 to 70 feet!
 * The Torturer in II will ventilate you instantly with his M60 machine gun if you get in his sights at close range. Ditto for Sanchez, who you have to take out by throwing a grenade into his hiding place.
 * Likewise, in Kane and Lynch 2:Dog Days, taking a bullet at point-blank range usually results in an instant death.
 * Vindictus' Wake Up Call Boss, the Gnoll Chieftain, is the first major boss you face that primarily uses smash attacks on you, as opposed to normal attacks. At the level that you first face him, two to three hits with his giant hammer are enough to kill you, and one of his smash attacks is a powerful whirlwind sweep which clears a sizable radius around him, making staying out of range and using hit-and-run tactics as he's recovering from a smash key to surviving the battle. Higher-level players have an easier time dealing with him, both due to experience in dealing with such bosses and having better armor and more HP.
 * Player example in the classic Doom games, if the player is packing the BFG. One shot at point-blank range downs everything in the game except for bosses.
 * Even then it is capable of taking out the Spider Mastermind in a single shot. (And tables on the Doom wiki indicate it is theoretically possible to do the same to the Cyberdemon. Only theoretically, though, the random numbers of the damage make that practically impossible.)
 * While many Touhou bosses have attacks that are downright impossible to survive in melee (as opposed to only nigh-impossible at range), special mention must go to Subterranean Animism's Yuugi Hoshiguma, whose "Knockout in Three Steps" literally inverts this trope. The attack generates a few bullets adjacent to her, before covering everything outside a certain radius with bullets; the only way to survive is to go up close, thus remaining inside the non-instant death radius.
 * In Warhammer 40000 Space Marine multiplayer, getting in line-of-sight of someone with a braced heavy bolter or melee range of someone with a Thunderhammer and Killing Blow is instant death, but only if they're looking at you.
 * The Flowsand Lord in Final Fantasy Tactics a 2 has an attack that works like this: Enemies within its massive range get pulled onto tiles right next to him and get hit with a large amount of damage, which he absorbs to heal himself. And its range is so large that once you're hit with it, it's next to impossible for a character to move out of range before he uses it again. There are only five classes in the entire game that can hit him from outside the range of his attack, and you fight him early enough that you're unlikely to have any of those classes.
 * In Dragon Age II, the duel with the Arishok can be really easy or really hard depending on what type of character you are playing. The Arishok has no ranged attacks, but makes up for that with brutal melee attacks. He's also pretty fast, so staying out of his Instant Death Radius while trying to attack him or drink a healing potion isn't easy. Mage!Hawke, despite being a Squishy Wizard, has an advantage since mage staff attacks are ranged.
 * Used to ludicrously unfair effect in Devil Survivor, where one late-game boss, Belberith, has an Instant Death Radius of the entire map you fight him on.
 * In the sequel, Devil Survivor 2, the final boss,, has this in it's first form and with one of it's components in it's third form as well. Said component follows up on this with the wonderful attack Multi-Strike that can potentially hit everyone in the party two to seven times for 200+ physical damage per hit, where you'll most likely have about 500 Hit Points for the main characters by that point, if not lower. Thankfully though, equipping Null/Absorb/Repel Physical will stop the nightmare.
 * Several examples in Dark Souls exist, particularly the boss fight with Seath the Scaleless. His attacks consist of area denial by raising crystal columns in predetermined spots. While you can dodge it and get close to him, you better not take it for granted as Seath can make the entire surrounding area you fight in covered in crystals. And if you don't die from it already, the Curse effect probably will.
 * Interestingly, the miracle Wrath of (the) God(s) in both Dark Souls and Demons Souls function the same: an exploding sphere of pain.
 * Quelaag and Nito both have powerful area of effect attacks similar to the Wrath of the Gods. Avoiding Quelaag's can be tricky thanks to the lava she spits out throughout the battle.
 * Armored Core for Answer has Assault Armors, which is also an exploding sphere of pain, usually a Useless Useful Spell done by the player. However, a certain Battleship Raid boss called The Answerer can also do this. And while it takes ages to charge, get caught in it and you might as well kiss 4/5ths of your health goodbye. On a related note, thanks to the plethora of heavy missiles and laser cannons on the underside, approaching it from the bottom is hazardous for your health.
 * In Sengoku Basara, several of the Mighty Glacier fighters have this going on, especially if you take their Super Arts into account. Going into melee with Honda Tadakatsu, Tachibana Muneshige or Shimazu Yoshihiro (and especially getting caught in their Super Arts) can cost you a significant amount of your health bar in an instant. Oda Nobunaga takes this to extremes in the third game, however: When channeling his gigantic demonic Super Mode, he cannot be flinched, his attacks have titanic reach, deal horrible damage, and juggles you to boot. The only way to deal with him if you don't have a good ranged attack (preferably with knockback) is to simply run away until he stops channelling it.
 * Freedom Force vs. the Third Reich puts the instant death radius on your side. Tricolor has no ranged attacks, and she's painfully frail, but her sword attacks can annihilate anything that gets close. Learn how to lure enemies around corners, and your only threats will be enemies that are instant-deathier than she is.
 * Dungeon Crawl has hydras, which get to make an attack with each head every turn. Unless you have a fire-branded slashing weapon to lop off their heads or ridiculous AC and damage reduction, fighting an eight-headed hydra in melee is a losing proposition. The unique boss the Lernean Hydra has twenty-seven heads and can do enough damage per round to kill a mid-level character four times over, making engaging it in melee a very quick means of suicide.
 * In No More Heroes, once Shinobu starts charging her Desperation Attack (Gengoken), run for your life! If it connects, you will die.
 * Touching any boss or miniboss enemy in Mickey Mousecapade is instant death.