Leviathan 
Creature — Leviathan
Trample This creature enters tapped and doesn't untap during your untap step. At the beginning of your upkeep, you may sacrifice two Islands. If you do, untap this creature. This creature can't attack unless you sacrifice two Islands. (This cost is paid as attackers are declared.)
Legality
standardNOT LEGALpioneerNOT LEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL