He is the fusion of Razputin's and Lil' Oly's dads. He is just as large as the original Butcher from the previous two battles, and wields both of the dads' powers, including two butcher knives and Raz's dad's flaming spiked juggling pins. Having been thrown into the meat grinder in the previous boss battle, he is a mutilated mess of limbs sewn together from both fathers.
When Raz is in his colossal psychic state, Two-Headed Dad Monster will cower in place, attempting to shield itself with its cleavers. Punch him as much as you can during this time before the psychic energy drains, and Raz is reverted back to normal. While in normal form, all the player can do is dodge and defend against his attacks while Raz's colossal state recharges. The best way to do this is to equip the Shield ability and keep moving. Alternatively, you can use Invisibility to hide until your transformation power is refilled.