The double-headed Nillious main motive in brawls is to kill - not to win. He does not like fighting as a team with his partner, Nillious is out to satisfy only himself. He likes to go rogue. Each head has its own personality & ability. Untamable & vicious, Magnus has his hands full keeping Nillious in line.
Hyper Nillious fist appeared in Mask of Power where he battled Drago and won, but immediately reverted back after Magnus's gauntlet malfunctioned.