Lair of the Hydra from Adventures in the Forgotten Realms can become a hydra itself, so it almost counts as two cards
Trample, haste, annihilator 1 (Whenever this creature attacks, defending player sacrifices a permanent of their choice.) Creature - Eldrazi Color tag templates(None) Inversion Behemoth At the beginning of combat on your turn, switch the power and toughness of each of any number of target creatures until end of turn
If you want some real fun, mutate this onto King Macar, the Gold-Cursed
There, there was talk of going green because it is necessary to go for multi-color reasons such as mana pumping, and since the existing Tutor is black, there was talk of making it green and black, but Future Sight's lead developer Mike Turian said that he would prefer this ability from white and went to white green
Declare Blockers step Once the attacking player has declared all of their attacking creatures, the defending player gets to declare their own blockers