Keszin, Moonportal Savant

Lifelink
{5}{w}{w}, {t}, Discard a card: Exile all other permanents. For as long as any of those cards remain exiled, at the beginning of each player's upkeep, that player returns one of the exiled cards they own to the battlefield. Activate this ability only any time you could cast a sorcery and only if you own no cards in exile that were exiled by Keszin, Moonportal Savant.