The ends justify the means.

You really want to be stronger. You want to know cooler spells, see more of the world, be taller. The other monsters are gonna die again and again anyway, so what's the harm ultimately?

And so you begin your strategy. Your grindy, grindy strategy. If the XP share from a boss was only almost enough to level you up, of course an ordinary monster will give very little. But you're patient. As long as you can keep yourself alive, you can wait it all out. And you do. Through a mix of cunning and cowardice you manage to avoid **** at every hero encounter, and slowly accumulate XP from fellow monsters. At first you try it on only slimes, since in case they notice what you're doing and disapprove, they can communicate it the least and will provide the least of a threat. Then you work your way up to giant rat, to skeleton, to goblin. Nobody seems to mind. Perhaps they can't tell the difference between your buffs and debuffs. Regardless, you keep up your strategy for a long time, you're not sure how long due to how there's no way of keeping track of time within the walls of the dungeon. However, one day, it finally happens.

You're standing behind a group of goblins and rats fighting a hero duo consisting of a mage and a warrior, and perform your usual routine of casting Curse and Hex on the monsters. And when the second goblin falls, you hear a delightful *Ding!*

Once they're all dead you run away, and are relieved to hear that the heroes don't come after you. Just as you hoped. A while back you started to notice that heroes ignore you, sometimes mentioning how you're "one of the bugged ones". Apparently your reversed strategy has been acknowledged, and it's made heroes more lenient towards you. That has made your plan to stay alive for long enough to level up at lot easier than it otherwise would have been, in fact you're pretty sure you would never had gotten this far had this not been the case.

You lean against a wall and open your stat menu, excitement coursing through you.

Dark Caster
Lvl: 5
Melee Attack: 0
Ranged Attack: 0
Armor: 0
Weakness: Melee
Special Abilities:
Hex: Reduces target's damage resistance by -30% for 20 seconds.
Curse: Reduces target's attack damage by -30% for 20 seconds.
Ward: Increases target's damage resistance by +30% for 30 seconds.
Empower: Increases target's attack damage by +30% for 30 seconds.

Ability Gained!
Corrode: Damages target's armor and weapon by 20 durability.

Hm. That's... good? Not great. In fact, not at all what you hoped for. A minor boost to your old spells and one new spell. Which is of course really exciting, your power is finally growing, but... it's just another debuff. You really want an offensive spell. You sigh to yourself. Maybe you just don't have one? Maybe you will, even at level 100, still be perfectly useless without someone to fight for you?

...No, you can't think like that! You actually leveled up after all this time, and that counts for something! You just gotta keep at it. You have to remain patient. Patient and cautious.