Geralf's Warmonger

Geralf's Warmonger enters the battlefield tapped and doesn't untap during its controller's untap step.
Delirium - At the beginning of each upkeep, if there are four or more card types among cards in your graveyard, untap Geralf's Warmonger. It gains all abilities of all creature cards in your opponents' graveyards until end of turn.
A twisted creature for a twisted purpose.