Death,Depravity And the Derandged

I don't really know where I'm going with this but it's going to be dark. the children are going to be put in a government facility to be trained as the world's best assassin's for 4 years. the first year will be basic training the second year will be intense torture until they get there mutated power. the third year will be training the power and the fourth will be a survival game in teams. the mutated powers are the body's defence system to the sort of torture they are given if they are repeatedly drown they my develop gills in they are burned they would develop scales or something similar. anyway this is my first novel idk how it will go but enjoy. Also there will be a harem not a big one like 4 people and there could be some lemon depending on how I feel.