Frostwalk Bastion - Modern Horizons - 240

Snow Land

{T}: Add {C}.
{1}{S}: Until end of turn, this land becomes a 2/3 Construct artifact creature. It's still a land. ({S} can be paid with one mana from a snow source.)
Whenever this land deals combat damage to a creature, tap that creature and it doesn't untap during its controller's next untap step.

Uncommon · Modern Horizons · #240 (MH1)

Illustrated by Jedd Chevrier