The Castle of Aincrad

The Castle of Aincrad enters the battlefield
tapped.
At the beginning of your upkeep, you may tap
one or more untapped creatures you control. For
each creature tapped this way, put floor counters
on Aincrad equal to that creature's power. Then
if Aincrad has 100 or more floor counters, you
win the game.
{t}: Add {c}.