Drumbellower

Flying
Untap all creatures you control during each other player's untap step.

Prosper, Tome-Bound

Deathtouch
Mystic Arcanum — At the beginning of your end step, exile the top card of your library. Until the end of your next turn, you may play that card.
Pact Boon — Whenever you play a card from exile, create a Treasure token.

Unstoppable Plan

At the beginning of your end step, untap all nonland permanents you control.

Seedborn Muse

Untap all permanents you control during each other player's untap step.

Sol Ring

Kiora's Follower

Prop Room

Untap each creature you control during each other player's untap step.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Dazzling Theater

Creature spells you cast have convoke. (Your creatures can help cast those spells. Each creature you tap while casting a creature spell pays for {1} or one mana of that creature's color.)
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Dazzling Theater // Prop Room

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Urianger Augurelt

Whenever you play a land from exile or cast a spell from exile, you gain 2 life.
Draw Arcanum — {T}: Look at the top card of your library. You may exile it face down.
Play Arcanum — {T}: Until end of turn, you may play cards exiled with Urianger Augurelt. Spells you cast this way cost {2} less to cast.