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.
• Umbral Mantle✓

  3

  Artifact — EquipmentC

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Staff of Domination✓

  3

  ArtifactC

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Sky Hussar

  3WU

  Creature — Human KnightUW

  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.
• Aura of Dominion

  UU

  Enchantment — AuraU

  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.
• Sword of the Paruns✓

  4

  Artifact — EquipmentC

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Copperhorn Scout

  G

  Creature — Elf ScoutG

  Copperhorn Scout untaps all (or many) permanents, refreshing Howlsquad Heavy's tap activation.
• Goblin Rabblemaster

  2R

  Creature — Goblin WarriorR

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

  2R

  EnchantmentR

  Both cards produce the same kind of effect (shared token subtype).
• White Plume Adventurer

  2W

  Creature — Orc ClericW

  White Plume Adventurer untaps all (or many) permanents, refreshing Howlsquad Heavy's tap activation.
• Great Goblin, Foul-Hearted

  3BR

  Legendary Creature — Goblin NobleBR

  Both cards produce the same kind of effect (shared token subtype).
• Jace, Ingenious Mind-Mage

  4UU

  Legendary Planeswalker — JaceU

  Jace, Ingenious Mind-Mage untaps all (or many) permanents, refreshing Howlsquad Heavy's tap activation.
• Bothersome Noisemaker

  1R

  Creature — Goblin BardR

  Both cards produce the same kind of effect (shared token subtype).
• Neriv, Crackling Vanguard

  2RWB

  Legendary Creature — Spirit DragonBRW

  Both cards produce the same kind of effect (shared token subtype).
• The Thirteenth Doctor

  1GU

  Legendary Creature — Time Lord DoctorGU

  The Thirteenth Doctor untaps all (or many) permanents, refreshing Howlsquad Heavy's tap activation.
• Tuktuk the Explorer

  2R

  Legendary Creature — GoblinR

  Both cards produce the same kind of effect (shared token subtype).
• Great Ugly-Looking Goblin // Clap! Snap!

  5B1B

  Creature — Goblin Soldier // Sorcery — AdventureB

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

  2W

  Creature — SpiritW

  Drumbellower untaps all (or many) permanents, refreshing Howlsquad Heavy's tap activation.
• Gideon, Martial Paragon

  4W

  Legendary Planeswalker — GideonW

  Gideon, Martial Paragon untaps all (or many) permanents, refreshing Howlsquad Heavy's tap activation.
• Down, Down to Goblin-town

  2B

  Enchantment — SagaB

  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 Howlsquad Heavy's tap activation.
• Intellectual Offering

  4U

  InstantU

  Intellectual Offering untaps all (or many) permanents, refreshing Howlsquad Heavy's tap activation.
• Gleeful Demolition

  R

  SorceryR

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

  2R

  Creature — Goblin SoldierR

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

  R

  Creature — GoblinR

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