Confidence:StrongSolidPlausibleTentativeSpeculative

• Intruder Alarm

  2U

  EnchantmentU

  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.
• Pia Nalaar, Consul of Revival

  RW

  Legendary Creature — Human ArtificerRW

  Both cards produce the same kind of effect (shared token subtype).
• Lita, Mechanical Engineer

  2W

  Legendary Artifact Creature — ArtificerW

  Lita, Mechanical Engineer untaps all (or many) permanents, refreshing Hangarback Walker's tap activation.
• Emry, Lurker of the Loch

  2U

  Legendary Creature — Merfolk WizardU

  Hangarback Walker is a free artifact, so Emry, Lurker of the Loch's affinity cost drops the moment it is on the battlefield.
• Jace, Ingenious Mind-Mage

  4UU

  Legendary Planeswalker — JaceU

  Jace, Ingenious Mind-Mage untaps all (or many) permanents, refreshing Hangarback Walker's tap activation.
• Aggravated Assault

  2R

  EnchantmentR

  Aggravated Assault untaps all (or many) permanents, refreshing Hangarback Walker's tap activation.
• Veteran Beastrider

  1GW

  Creature — Human KnightGW

  Veteran Beastrider untaps all (or many) permanents, refreshing Hangarback Walker's tap activation.
• Saheeli, Jewel of Avishkar

  2UR

  Legendary Creature — Human ArtificerRU

  Both cards produce the same kind of effect (shared token subtype).
• Retrofitter Foundry

  1

  ArtifactC

  Both cards produce the same kind of effect (shared token subtype).
• Dazzling Theater // Prop Room

  3W2W

  Enchantment — Room // Enchantment — RoomW

  Dazzling Theater untaps all (or many) permanents, refreshing Hangarback Walker's tap activation.
• Ivorytusk Fortress

  2WBG

  Creature — ElephantBGW

  Ivorytusk Fortress untaps all (or many) permanents, refreshing Hangarback Walker's tap activation.
• Unstoppable Plan

  2U

  EnchantmentU

  Unstoppable Plan untaps all (or many) permanents, refreshing Hangarback Walker's tap activation.
• Plargg, Dean of Chaos // Augusta, Dean of Order

  1R2W

  Legendary Creature — Orc Shaman // Legendary Creature — Human ClericRW

  Plargg, Dean of Chaos untaps all (or many) permanents, refreshing Hangarback Walker's tap activation.
• Najeela, the Blade-Blossom

  2R

  Legendary Creature — Human WarriorBGRUW

  Najeela, the Blade-Blossom untaps all (or many) permanents, refreshing Hangarback Walker's tap activation.
• Betor, Kin to All

  2WBG

  Legendary Creature — Spirit DragonBGW

  Betor, Kin to All untaps all (or many) permanents, refreshing Hangarback Walker's tap activation.
• Combat Celebrant

  2R

  Creature — Human WarriorR

  Combat Celebrant untaps all (or many) permanents, refreshing Hangarback Walker's tap activation.
• Aurelia, the Warleader

  2RRWW

  Legendary Creature — AngelRW

  Aurelia, the Warleader untaps all (or many) permanents, refreshing Hangarback Walker's tap activation.
• Voyage Home

  5WU

  SorceryUW

  Hangarback Walker is a free artifact, so Voyage Home's affinity cost drops the moment it is on the battlefield.
• Unwinding Clock

  4

  ArtifactC

  Unwinding Clock untaps all (or many) permanents, refreshing Hangarback Walker's tap activation.
• Ahn-Crop Champion

  2GW

  Creature — Human WarriorGW

  Ahn-Crop Champion untaps all (or many) permanents, refreshing Hangarback Walker's tap activation.
• Anzrag, the Quake-Mole

  2RG

  Legendary Creature — Mole GodGR

  Anzrag, the Quake-Mole untaps all (or many) permanents, refreshing Hangarback Walker's tap activation.
• Refurbished Familiar

  3B

  Artifact Creature — Zombie RatB

  Hangarback Walker is a free artifact, so Refurbished Familiar's affinity cost drops the moment it is on the battlefield.
• Port Razer

  3RR

  Creature — Orc PirateR

  Port Razer untaps all (or many) permanents, refreshing Hangarback Walker's tap activation.
• Intrude on the Mind

  3UU

  InstantU

  Both cards produce the same kind of effect (shared token subtype).
• Thoughtcast

  4U

  SorceryU

  Hangarback Walker is a free artifact, so Thoughtcast's affinity cost drops the moment it is on the battlefield.