Confidence:StrongSolidPlausibleTentativeSpeculative

• Fiery Gambit

  2R

  SorceryR

  Fiery Gambit untaps all (or many) permanents, refreshing Ancient Den's tap activation.
• Innocuous Researcher

  3G

  Creature — Centaur DetectiveG

  Innocuous Researcher untaps all (or many) permanents, refreshing Ancient Den's tap activation.
• Magus of the Candelabra

  G

  Creature — Human WizardG

  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.
• Candelabra of Tawnos

  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.
• Voyage Home

  5WU

  SorceryUW

  Ancient Den is a free artifact, so Voyage Home's affinity cost drops the moment it is on the battlefield.
• Beledros Witherbloom

  5BG

  Legendary Creature — Elder DragonBG

  Beledros Witherbloom untaps all (or many) permanents, refreshing Ancient Den'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.
• Refurbished Familiar

  3B

  Artifact Creature — Zombie RatB

  Ancient Den is a free artifact, so Refurbished Familiar's affinity cost drops the moment it is on the battlefield.
• Saryth, the Viper's Fang

  2GG

  Legendary Creature — Human WarlockG

  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.
• Prophet of Kruphix

  3GU

  Creature — Human WizardGU

  Prophet of Kruphix untaps all (or many) permanents, refreshing Ancient Den's tap activation.
• Emry, Lurker of the Loch

  2U

  Legendary Creature — Merfolk WizardU

  Ancient Den is a free artifact, so Emry, Lurker of the Loch's affinity cost drops the moment it is on the battlefield.
• Assert Authority

  5UU

  InstantU

  Ancient Den is a free artifact, so Assert Authority's affinity cost drops the moment it is on the battlefield.
• Bumi, Unleashed

  3RG

  Legendary Creature — Human Noble AllyGR

  Bumi, Unleashed untaps all (or many) permanents, refreshing Ancient Den's tap activation.
• Thoughtcast

  4U

  SorceryU

  Ancient Den is a free artifact, so Thoughtcast's affinity cost drops the moment it is on the battlefield.
• Thought Monitor

  6U

  Artifact Creature — ConstructU

  Ancient Den is a free artifact, so Thought Monitor's affinity cost drops the moment it is on the battlefield.
• Chiss-Goria, Forge Tyrant

  6RRR

  Legendary Creature — DragonR

  Ancient Den is a free artifact, so Chiss-Goria, Forge Tyrant's affinity cost drops the moment it is on the battlefield.
• 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 Ancient Den's tap activation.
• Wilderness Reclamation

  3G

  EnchantmentG

  Wilderness Reclamation untaps all (or many) permanents, refreshing Ancient Den's tap activation.
• Seedborn Muse

  3GG

  Creature — SpiritG

  Seedborn Muse untaps all (or many) permanents, refreshing Ancient Den's tap activation.
• Sojourner's Companion

  7

  Artifact Creature — SalamanderC

  Ancient Den is a free artifact, so Sojourner's Companion's affinity cost drops the moment it is on the battlefield.
• Sword of Feast and Famine

  3

  Artifact — EquipmentC

  Sword of Feast and Famine untaps all (or many) permanents, refreshing Ancient Den's tap activation.
• Ethersworn Sphinx

  7WU

  Artifact Creature — SphinxUW

  Ancient Den is a free artifact, so Ethersworn Sphinx's affinity cost drops the moment it is on the battlefield.
• 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.
• Imskir Iron-Eater

  6BR

  Legendary Creature — DemonBR

  Ancient Den is a free artifact, so Imskir Iron-Eater's affinity cost drops the moment it is on the battlefield.