Effluence Devourer

W, T: Draft a card from Celestial Vault's spellbook and exile it face down. 1, Sacrifice Celestial Vault: Put each card exiled with Celestial Vault into your hand.

Flying When Herald of Vengeance enters the battlefield, destroy each permanent you don't control that has the same name as a permanent that dealt damage to you last turn.

Flying When this creature enters, return a permanent you control to its owner's hand. If it's a non-Angel creature card, it perpetually gets +1/+1, gains flying, and becomes an Angel in addition to its other types.

2, T: Choose target opponent. Conjure a duplicate of the top card of their library into your hand. It perpetually gains "You may spend mana as though it were mana of any color to cast this spell." Then they exile the top card of their library face down.

Seek two cards. You may shuffle them into your library. If you do, seek two cards. You have no maximum hand size for the rest of the game.

Flash When this creature enters, return target nonland permanent an opponent controls to its owner's hand. It perpetually gains "This spell costs 2 more to cast."

As an additional cost to cast this spell, you may sacrifice a non-Demon creature. Flying When Graven Archfiend enters the battlefield, if its additional cost was paid, conjure a card named Demonic Pact onto the battlefield.

Casualty 1 (As you cast this spell, you may sacrifice a creature with power 1 or greater. When you do, copy this spell and you may choose a new target for the copy.) Target creature an opponent controls perpetually gets -0/-3.