Battle Stadium

Indestructible
{t}: Add {c}
Battle Stadium enters the battlefield with 5 catch counters.
At the beginning of your upkeep; if it has 0 catch counters sacrifice it. If it has 30 you win the game.
Whenever a catch counter is placed on another permanent, place a catch counter on Battle Stadium.
Whenever a creature with a catch counter deals combat damage to one of your opponents, remove a catch counter from Battle Stadium.