The Whig Brothers

The three brothers are the Whigmaster, Miwhayt, and Azeroth. They are the third boss you fight. It is hard because you need to beat 3 bosses, each having a P3 and a rage mode (hereafter referred to as "enraged") each phase (excluding Whigmaster), all at the same time. The Whigmaster remains the same as in his fight, though he is weakened because you destroyed him in that fight.