Confidence:StrongSolidPlausibleTentativeSpeculative

• Splinter Twin✓

  2RR

  Enchantment — AuraR

  Copy chain: one card creates hasty copies of a creature whose ability or ETB the partner exploits — the canonical Kiki-Jiki / Splinter Twin pattern.
• Hazel of the Rootbloom

  2BG

  Legendary Creature — Squirrel DruidBG

  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.
• Jace, Vryn's Prodigy // Jace, Telepath Unbound

  1U

  Legendary Creature — Human Wizard // Legendary Planeswalker — JaceU

  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.
• Thraben Doomsayer

  1WW

  Creature — Human ClericW

  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.
• Elvish Scout

  G

  Creature — Elf ScoutG

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Terra, Magical Adept // Esper Terra

  1RG

  Legendary Creature — Human Wizard Warrior // Legendary Enchantment Creature — Saga WizardBGRUW

  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.
• Xavier Sal, Infested Captain

  BGU

  Legendary Creature — Human Fungus PirateBGU

  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.
• Joo Dee, One of Many

  1B

  Creature — Human AdvisorB

  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.
• Samut, Voice of Dissent

  3RG

  Legendary Creature — Human WarriorGRW

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

  2

  Legendary ArtifactC

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

  2U

  Creature — Merfolk DetectiveU

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

  3W

  Legendary Creature — Time Lord ScientistW

  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.
• Osgood, Operation Double

  2UU

  Legendary Creature — Human Alien ShapeshifterU

  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.
• Seeker of Skybreak

  1G

  Creature — ElfG

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

  G

  Enchantment — AuraG

  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.
• Careful Cultivation

  2G

  Enchantment — AuraG

  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.
• Saryth, the Viper's Fang

  2GG

  Legendary Creature — Human WarlockG

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Dion, Bahamut's Dominant // Bahamut, Warden of Light

  3W

  Legendary Creature — Human Noble Knight // Legendary Enchantment Creature — Saga DragonW

  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.
• Dino DNA

  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.
• Second Wind

  2U

  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.
• Norritt

  3B

  Creature — ImpB

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Ioreth of the Healing House

  2U

  Legendary Creature — Human ClericU

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

  1U

  Creature — Merfolk WizardU

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Joshua, Phoenix's Dominant // Phoenix, Warden of Fire

  1RW

  Legendary Creature — Human Noble Wizard // Legendary Enchantment Creature — Saga PhoenixRW

  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.
• Vizier of Tumbling Sands

  2U

  Creature — Human ClericU

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

• WithTempestra, Dame of Games1RR

  Copy chain: each card copies the other (or both copy a third), generating arbitrary copies. These two can't keep the loop going alone — add one of these to complete it:

  Magda, Brazen Outlaw1RRose Room Treasurer3RSharp-Eyed Rookie1GKingpin, Wilson Fisk3BGemcutter Buccaneer3RGanax, Astral Hunter4R
  Show cards