Master of the Monster Lair

Owen is a young boy from the sleepy town of South Arc. The Mayor is dismayed by his town's lack of exciting tourist attractions, so he gets a really bright idea - get someone (Owen) to build a dungeon in the nearby cave to attract monsters. Upon discovering a talking magic shovel, Owen is given the daunting task by the Mayor of transforming the town's only cave into something a hero would be proud of.

As the aspiring eponymous Master of the Monster Lair, Owen must use his shovel to dig holes in the dungeon and create rooms for monsters to spawn in so that Owen (and presumably other future heroes) can fight them.

Tropes used in Master of the Monster Lair include:

Crossover: Owen and Kate also appear in My World, My Way.
Dungeon Crawling
HP to One: The "Weaken" Magic.
Hub Level: The town.
Item Farming: Owen and Kate raise their stats by eating food. Almost all decent food requires at least one ingredient you can't purchase in town. Half the time, fighting an enemy gets you equipment or Vendor Trash rather than the food you're looking for. Do the math.
Life Drain
Non-Human Sidekick: Gloop the slime, who joins Owen after a few days.
Power Copying: While Owen and Kate raise their stats by eating food every day, Gloop has a chance of mimicking a body part of an enemy monster after every fight. What he's copying at the moment determines his stats, special attacks, and possible equipment. The only thing that persists between forms is learned spells; he can learn spells by copying the Head of certain monsters.
The Reveal: King Leon was using you to set up a dungeon as his base of operations to take over the world before the Devil Prince can.
Vendor Trash: Animal enemies have a tendency to drop pelts. Humanoid enemies have a tendency to drop coins.
We Buy Anything: The weapon/armor shop purchases any items/equipment you find.