Helm's Deep

Indestructible
Helm's Deep enters the battlefield with 3 day counters on it. At the beginning of your upkeep,
remove a day counter from Helm's Deep. Other Creatures you control gain defender
and reach. When there are no day counters on
Helm's Deep, you win the game.
{4}, Sacrifice a creature with power 4 or greater,
exile Helm's Deep. Any player may activate this ability