Confidence:StrongSolidPlausibleTentativeSpeculative

• Intellectual Offering

  4U

  InstantU

  Intellectual Offering untaps all (or many) permanents, refreshing Altar of Shadows's tap activation.
• Formidable Speaker

  2G

  Creature — Elf DruidG

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• Unstoppable Plan

  2U

  EnchantmentU

  Unstoppable Plan untaps all (or many) permanents, refreshing Altar of Shadows's tap activation.
• Esper Sojourners

  WUB

  Artifact Creature — Vedalken WizardBUW

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• Voltaic Key

  1

  ArtifactC

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• Unwinding Clock

  4

  ArtifactC

  Unwinding Clock untaps all (or many) permanents, refreshing Altar of Shadows's tap activation.
• Seedborn Muse

  3GG

  Creature — SpiritG

  Seedborn Muse untaps all (or many) permanents, refreshing Altar of Shadows's tap activation.
• Manifold Key

  1

  ArtifactC

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• Sonic Screwdriver

  3

  ArtifactC

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• Paradox Engine

  5

  Legendary ArtifactC

  Paradox Engine untaps all (or many) permanents, refreshing Altar of Shadows's tap activation.
• Captain of the Mists

  2U

  Creature — Human WizardU

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• Galvanic Key

  2

  ArtifactC

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• Dramatic Reversal

  1U

  InstantU

  Dramatic Reversal untaps all (or many) permanents, refreshing Altar of Shadows's tap activation.
• Filigree Sages

  3U

  Artifact Creature — Vedalken WizardU

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• The Pandorica

  2W

  Legendary ArtifactW

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• Elder Druid

  3G

  Creature — Elf Cleric DruidG

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• Blinkmoth Infusion

  12UU

  InstantU

  Blinkmoth Infusion untaps all (or many) permanents, refreshing Altar of Shadows's tap activation.
• Mr. House, President and CEO

  RWB

  Legendary Artifact Creature — HumanBRW

  Mana loop: net-positive mana cycle between the two cards.
• Currency Converter

  1

  ArtifactC

  Mana loop: net-positive mana cycle between the two cards.
• Wizard's Rockets

  1

  ArtifactC

  Mana loop: net-positive mana cycle between the two cards.
• Reckless Lackey

  R

  Creature — Goblin PirateR

  Mana loop: net-positive mana cycle between the two cards.
• Ashnod, Flesh Mechanist

  B

  Legendary Creature — Human ArtificerB

  Mana loop: net-positive mana cycle between the two cards.
• Petalmane Baku

  1G

  Creature — SpiritG

  Mana loop: net-positive mana cycle between the two cards.
• Fain, the Broker

  2B

  Legendary Creature — Human WarlockB

  Mana loop: net-positive mana cycle between the two cards.
• Nykthos, Shrine to Nyx

  Legendary LandC

  Mana loop: net-positive mana cycle between the two cards.