Katharsin, Deep Terror

Whenever an opponent casts a non-artifact spell, that player puts the top X cards of his or her library into his or her graveyard, where X is that spells converted mana cost.
{u/b}{u/b}{t}: Exile all cards from target opponent's graveyard
{u}{b}{t}: Exile all cards from all graveyards
{u}{u}{b}{b}{t}: Exile all cards from each opponent's graveyard