If you get killed by a particular enemy in a level, the next time you retry the level that enemy will be leveled up some.
It turns “oh this part is hard for me” into “JFCWTF?!” which is good for people who like to be frustrated and hate themselves, and also can make it feel like there’s more story development instead of replaying exactly the same level again and again
This seems like a great way to ensure that the player can't beat the level. I assume there's a maximum difficulty where the enemy is still possible to beat?
Also, when does the boosted difficulty reset for the level? After beating it? I am not a fan of frustrating games, so I can't even imagine playing a game like this without just quitting.