Evigishki Tetrogre

Vigilance, Ritual Summon 6 - Gishki
{u}{b}: Choose from one of the following card
types - creature, noncreature permanent, or non-permanent. Target opponent may discard a card.
If that player doesn't, you and that player each
search their library for a card of the chosen type,
and put them into their respective graveyards.
Play this ability once per turn, and only as a
sorcery.