Serpent of Surtur

Flying, Defender, Haste, Vigilance
{r}{r}{r}: Give Serpent of Surtur +X/+X where X
is the number of flying creatures on the
battlefield. (Use this ability as an instant)
{4}: Serpent of Surtur loses defender
Every knight that has ever fought the Serpent of
Surtur has never lived to tell the tale