Zirilan, the Pact Keeper

Vigilance
{t}: Add {r}. Spend this mana only to cast a
Dragon spell.
{x}{r}{r},{t}: Search your library for a Dragon
creature card with mana value X or less and put
it onto the battlefield, then shuffle. If X is 10 or
more, creatures you control get +X/+X and gain
haste until end of turn.
"Guess whos back."
—Ertai