Ook'mar, Skargoth Exemplar

Ritual {2}{u}{u}{b}{b}{r}{r} (Sacrifice any number of permanents you control as you cast this creature. If the total combined mana costs of those permanents is greater than or equal to the ritual cost, you may cast this creature without paying its mana cost.)
Sacrifice a creature you control: Gain control of target instant or sorcery with converted mana cost less than or equal to that of the sacrificed creature. Then copy that spell. You may choose new targets for the copy.