Confidence:StrongSolidPlausibleTentativeSpeculative

• Samut, Voice of Dissent✓

  3RG

  Legendary Creature — Human WarriorGRW

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Freed from the Real✓

  2U

  Enchantment — AuraU

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Pemmin's Aura✓

  1UU

  Enchantment — AuraU

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

  4

  Artifact — EquipmentC

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Thousand-Year Elixir✓

  3

  ArtifactC

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

  U

  Enchantment — AuraU

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

  1WU

  EnchantmentUW

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

  2W

  Enchantment — AuraW

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Tinybones Joins Up

  B

  Legendary EnchantmentB

  Both cards trigger when a creature enters the battlefield — they fire together.
• Spreading Plague

  4B

  EnchantmentB

  Both cards trigger when a creature enters the battlefield — they fire together.
• Season of Growth

  1G

  EnchantmentG

  Both cards trigger when a creature enters the battlefield — they fire together.
• Kiora, Behemoth Beckoner

  2G/U

  Legendary Planeswalker — KioraGU

  Both cards trigger when a creature enters the battlefield — they fire together.
• Kiora, Master of the Depths

  2GU

  Legendary Planeswalker — KioraGU

  Both cards trigger when a creature enters the battlefield — they fire together.
• Faramir, Steward of Gondor

  1WU

  Legendary Creature — Human NobleUW

  Both cards trigger when a creature enters the battlefield — they fire together.
• Eye of Singularity

  3W

  World EnchantmentW

  Both cards trigger when a creature enters the battlefield — they fire together.
• Massimo, the Magician

  URW

  Legendary Creature — Cat WizardRUW

  Both cards trigger when a creature enters the battlefield — they fire together.
• Warden of the Grove

  2G

  Creature — HydraG

  Both cards trigger when a creature enters the battlefield — they fire together.
• Copperhorn Scout

  G

  Creature — Elf ScoutG

  Copperhorn Scout untaps all (or many) permanents, refreshing Selvala, Heart of the Wilds's tap activation.
• Garruk, Curse Breaker

  3GG

  Legendary Planeswalker — GarrukG

  Both cards trigger when a creature enters the battlefield — they fire together.
• Grist, Voracious Larva // Grist, the Plague Swarm

  G

  Legendary Creature — Insect // Legendary Planeswalker — GristBG

  Both cards trigger when a creature enters the battlefield — they fire together.
• Fecund Greenshell

  3GG

  Creature — Elemental TurtleG

  Both cards trigger when a creature enters the battlefield — they fire together.
• Elvish Scout

  G

  Creature — Elf ScoutG

  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.
• Lonis, Cryptozoologist

  GU

  Legendary Creature — Snake Elf ScoutGU

  Both cards trigger when a creature enters the battlefield — they fire together.