Ilzros, Chosen to Devour

Flying, Haste, Vigilance
{2}{p/b}, {t}, Sacrifice a creature: Search your library
for a creature card with converted mana cost
equal to 1 plus the sacrificed creature's converted
mana cost, put that card onto the battlefield,
that creature is a Dragon in addition to its other
types, then shuffle your library.
Partner with Ratheous, Born From Exile.