Tiamat, Dragon Goddess

As additional cost, for each color, sacrifice a dragon you control. You can't sacrifice a shapeshifter this way.
Haste, Flying, FirstStrike, Trample, Indestructible.
When Tiamat enters in battlefield, it causes damage equal his power to each opponent and each creature them control.
{w}{u}{b}{r}{g}, Ascend (Exile this card, gain the Emblem: "For the rest of the game, you can't cast Tiamat"): Look in your hand. library, graveyard and exile zone for any number of dragons and put them on play.