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.
• 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

  Token-fuel engine: one side keeps producing untapped tokens that pay the other's tap costs, and the output feeds the loop again — Squirrel Nest with Earthcraft is the classic shape.
• Preacher of the Schism

  2B

  Creature — Vampire ClericB

  Both cards produce the same kind of effect (shared token subtype).
• Clavileño, First of the Blessed

  1WB

  Legendary Creature — Vampire ClericBW

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

  G

  Creature — Elf ScoutG

  Copperhorn Scout untaps all (or many) permanents, refreshing Bloodline Keeper's tap activation.
• Sorin the Mirthless

  2BB

  Legendary Planeswalker — SorinB

  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 Bloodline Keeper's tap activation.
• Promise of Aclazotz // Foul Rebirth

  1B2B

  Enchantment // Sorcery — AdventureB

  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 Bloodline Keeper's tap activation.
• Glass-Cast Heart

  2B

  ArtifactB

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

  2R

  EnchantmentR

  Aggravated Assault untaps all (or many) permanents, refreshing Bloodline Keeper's tap activation.
• Sorin, Lord of Innistrad

  2WB

  Legendary Planeswalker — SorinBW

  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 Bloodline Keeper's tap activation.
• Veteran Beastrider

  1GW

  Creature — Human KnightGW

  Veteran Beastrider untaps all (or many) permanents, refreshing Bloodline Keeper's tap activation.
• Sorin, Grim Nemesis

  4WB

  Legendary Planeswalker — SorinBW

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

  XWW

  EnchantmentW

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

  2W

  Creature — SpiritW

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

  4W

  Legendary Planeswalker — GideonW

  Gideon, Martial Paragon untaps all (or many) permanents, refreshing Bloodline Keeper's tap activation.
• Sorin, Solemn Visitor

  2WB

  Legendary Planeswalker — SorinBW

  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 Bloodline Keeper's tap activation.
• Intellectual Offering

  4U

  InstantU

  Intellectual Offering untaps all (or many) permanents, refreshing Bloodline Keeper's tap activation.
• Prophet of Kruphix

  3GU

  Creature — Human WizardGU

  Prophet of Kruphix untaps all (or many) permanents, refreshing Bloodline Keeper's tap activation.
• Éomer, Marshal of Rohan

  2RR

  Legendary Creature — Human KnightR

  Éomer, Marshal of Rohan untaps all (or many) permanents, refreshing Bloodline Keeper's tap activation.
• Baron Bertram Graywater

  2WB

  Legendary Creature — Vampire NobleBW

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