Confidence:StrongSolidPlausibleTentativeSpeculative

• Innocuous Researcher

  3G

  Creature — Centaur DetectiveG

  Innocuous Researcher untaps all (or many) permanents, refreshing Spara's Headquarters's tap activation.
• Currency Converter

  1

  ArtifactC

  Spara's Headquarters has cycling, and Currency Converter pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• 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.
• Necropotence

  BBB

  EnchantmentB

  Spara's Headquarters has cycling, and Necropotence pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Stinkweed Imp

  2B

  Creature — ImpB

  Spara's Headquarters has cycling, and Stinkweed Imp pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• 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.
• Midnight Oil

  2BB

  EnchantmentB

  Spara's Headquarters has cycling, and Midnight Oil pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Insidious Roots

  BG

  EnchantmentBG

  Spara's Headquarters has cycling, and Insidious Roots pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Lazotep Chancellor

  UB

  Creature — Zombie WizardBU

  Spara's Headquarters has cycling, and Lazotep Chancellor pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Necroplasm

  1BB

  Creature — OozeB

  Spara's Headquarters has cycling, and Necroplasm pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Vash, Freelance Archaeologist

  1BG

  Legendary Creature — Human Rogue ScientistBG

  Spara's Headquarters has cycling, and Vash, Freelance Archaeologist pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• The Necrobloom

  1WBG

  Legendary Creature — PlantBGW

  Spara's Headquarters has cycling, and The Necrobloom pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Beledros Witherbloom

  5BG

  Legendary Creature — Elder DragonBG

  Beledros Witherbloom untaps all (or many) permanents, refreshing Spara's Headquarters'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.
• Green Goblin, Back for More

  3BB

  Legendary Creature — Goblin Human VillainB

  Spara's Headquarters has cycling, and Green Goblin, Back for More pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Ivora, Insatiable Heir

  1R

  Legendary Creature — Vampire WarriorR

  Spara's Headquarters has cycling, and Ivora, Insatiable Heir pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Ragged Recluse // Odious Witch

  1B

  Creature — Human Peasant // Creature — Human WarlockB

  Spara's Headquarters has cycling, and Ragged Recluse pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• 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 Spara's Headquarters's tap activation.
• Electro's Bolt

  2R

  SorceryR

  Spara's Headquarters has cycling, and Electro's Bolt pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Valiant Rescuer

  1W

  Creature — Human SoldierW

  Spara's Headquarters has cycling, and Valiant Rescuer pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Flameblade Adept

  R

  Creature — Jackal WarriorR

  Spara's Headquarters has cycling, and Flameblade Adept pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Bumi, Unleashed

  3RG

  Legendary Creature — Human Noble AllyGR

  Bumi, Unleashed untaps all (or many) permanents, refreshing Spara's Headquarters's tap activation.
• Prison Break

  4B

  SorceryB

  Spara's Headquarters has cycling, and Prison Break pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Flourishing Fox

  W

  Creature — FoxW

  Spara's Headquarters has cycling, and Flourishing Fox pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.