I found a bug with the extra loop level feature. I had taken Crown of Destiny and gotten a ninth mutation already, so when I double looped and hit 11, it didn't give me the extra mutation.
Also, mutation idea: Winning Smile, small chance for critical hits. Surprised NT never had a 'crit' mechanic to begin with.
Also, while I'm thinking of mutation ideas, Chiseled Chin, chance that destroying walls (or maybe props) will drop hp and ammo.