undead dungeon.

you find an undead dungeon. from what you understand, the dungeon master revived old bones at that location and used them to kill adventurers, revived them and repeat. you enter the dungeon. at the entrance there are 3 skeletons and a zombie. unsurprisingly, your punch, which destroyed dungeon walls, one-shotted the skeletons and zombie. the mechanical voice says "experience received. possible to level up to level 15". it seems like you will be able to farm experience from this dungeon. you continue to hunt there while searching for the boss room, when the voice(this is the mechanical voice) says "level 20 achieved. possible evolution for the core and the class.

monster evolution:
Minotaur warlord- the warlord, leader of the minotaurs during battle./perks: unshakable leadership- you are able to bestow some of your upon your subordinates. you keep the ability./ upgrade trait: if you have a core of the strong branch, upgrade it./ strength of the leader- increase physical strength and defense by 230% each. also increase magical defense by 450%.
Minotaur shaman- shaman, the tribal leader of the minotaurs who leads them according to the will of their god./will of the gods- you will gain the priest and sorcerer classes, regardless of your class./ upgrade trait: if you have a core of the arcane branch, upgrade it.

class upgrade:
shadow assassin:
ghost- you are specialized in stealth and sneaking. magical shadow time increase to 24 hours.
killer of the night- damage focused upgrade. increase damage of all kind and you are able to quadruple your strength or a minute.

warrior:
warrior of blood- you drenched yourself in madness to get stronger, however you are still rational.
warrior of honor- you have abandoned your ways of madness and became a man of honor.