Amethyst, Magician Supreme

Flying, prowess, magical
Spells that opponents cast targeting Amethyst, Magician Supreme cost {2} more to cast.
{4}{u}{u}{u}, {t}: Search your library for an instant or sorcery card, cast it without paying its mana cost, and exile it as it resolves. Then, if cards exiled with Amethyst have total converted mana cost 10 or greater, sacrifice Amethyst.
When Amethyst dies, put him onto the battlefield transformed.