Ice Titan

Landmorph {3}{u} (You may play this card face down as a snow land with "{t} : Add {u} to your mana pool." Turn it face up any time for its Landmorph cost.)
Whenever Ice Titan blocks or becomes blocked by a creature, that creature doesn't untap during its controller's next untap step.
At the beginning of your next turn, turn Ice Titan face down.