Reznor icon.
Reznor is the fourth and the final boss in BRAAAINS. It is available once the player reaches level 50. This means that the level fight between this and Ying Ying is 20 not 10. Killing it will give a powerful two handed Blade of Reznor, a powerful sword made of remnants of Rezznor which has 128 damage with 64 overall yet is a slow weapon. Killing this Boss will get the "Beast Slayer" Achievement for 10 brains. Reznor is a beast a fusion of a cattle/bull and a lion.