Confidence:StrongSolidPlausibleTentativeSpeculative

• 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.
• Elvish Scout

  G

  Creature — Elf ScoutG

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Samut, Voice of Dissent

  3RG

  Legendary Creature — Human WarriorGRW

  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.
• 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.
• Stonybrook Angler

  1U

  Creature — Merfolk WizardU

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Vizier of Tumbling Sands

  2U

  Creature — Human ClericU

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

  2U

  Creature — ElementalU

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

  5WU

  Legendary Creature — Human WizardUW

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

  LandC

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

  2U

  Creature — SpiritU

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

  GU

  Creature — MutantGU

  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.
• Zirda, the Dawnwaker

  1R/WR/W

  Legendary Creature — Elemental FoxRW

  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.
• Captain of the Mists

  2U

  Creature — Human WizardU

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

  2U

  Creature — Human WizardU

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

  2U

  Creature — BeastU

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

  3U

  Creature — Zombie WizardU

  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

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Saheeli, the Sun's Brilliance

  UR

  Legendary Creature — Human ArtificerRU

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

  1RW

  Legendary Creature — Human ClownRW

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

  3UU

  Creature — Elemental MinionU

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Minamo, School at Water's Edge

  Legendary LandU

  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.
• Nimbleclaw Adept

  3U

  Creature — Dragon WizardU

  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.

• 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:

  Sharp-Eyed Rookie1GGala Greeters1GRose Room Treasurer3RKingpin, Wilson Fisk3BGemcutter Buccaneer3RGanax, Astral Hunter4R
  Show cards