Rental Magica/YMMV


 * High Octane Nightmare Fuel
 * Yeah, just at the first (broadcast) episode an old man who supposed to be dead resurrected... wait, that's not an undead, it's like something from.... oh my! Eldritch Abomination!
 * And don't get us started with  in the fifth and sixth episode, who is a formless monster that can use any demonic form he desires...
 * Fin Cruda in the last three (broadcast) episodes, along with The Dragon, is what could be described by this troper "If Giygas has human form"...
 * Then there's the giant, floating larva in Sekiren's debut episode. (shudder) Coincidentally, it actually does have the power to cause nightmares in the show itself.