Tiamat, Evil Queen of Dragons

Dragons you control have indestructible.
Whenever a non-token Dragon enters the battlefield, put a 5/5 Dragon creature token with flying onto the battlefield.
Whenever a dragon you control dies, it deals damage equal to its power to any target.
{3}{w}{u}{b}{r}{g}, Sacrifice 12 Dragons with power 5 or more: You win the game.