Confidence:StrongSolidPlausibleTentativeSpeculative

• Intellectual Offering

  4U

  InstantU

  Intellectual Offering untaps all (or many) permanents, refreshing Key to the Side-Door's tap activation.
• Unstoppable Plan

  2U

  EnchantmentU

  Unstoppable Plan untaps all (or many) permanents, refreshing Key to the Side-Door's tap activation.
• Unwinding Clock

  4

  ArtifactC

  Unwinding Clock untaps all (or many) permanents, refreshing Key to the Side-Door's tap activation.
• Seedborn Muse

  3GG

  Creature — SpiritG

  Seedborn Muse untaps all (or many) permanents, refreshing Key to the Side-Door's tap activation.
• Paradox Engine

  5

  Legendary ArtifactC

  Paradox Engine untaps all (or many) permanents, refreshing Key to the Side-Door's tap activation.
• Dramatic Reversal

  1U

  InstantU

  Dramatic Reversal untaps all (or many) permanents, refreshing Key to the Side-Door's tap activation.
• Blinkmoth Infusion

  12UU

  InstantU

  Blinkmoth Infusion untaps all (or many) permanents, refreshing Key to the Side-Door's tap activation.
• Emrakul's Messenger

  1U

  Creature — Eldrazi Faerie RogueU

  Draw pair: both cards engage with card draw. With a damage-or-draw trigger between them they form a draw engine.
• Rom and Leeta, Unlikely Pair

  3R

  Legendary Creature — Ferengi BajoranR

  Draw pair: both cards engage with card draw. With a damage-or-draw trigger between them they form a draw engine.
• Kurkesh, Onakke Ancient

  2RR

  Legendary Creature — Ogre SpiritR

  Key to the Side-Door has activated abilities that aren't mana abilities, fueling Kurkesh, Onakke Ancient's activation-trigger.
• Rings of Brighthearth

  3

  ArtifactC

  Key to the Side-Door has activated abilities that aren't mana abilities, fueling Rings of Brighthearth's activation-trigger.