Confidence:StrongSolidPlausibleTentativeSpeculative

• Sword of the Paruns✓

  4

  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.
• Copperhorn Scout

  G

  Creature — Elf ScoutG

  Copperhorn Scout untaps all (or many) permanents, refreshing Rainveil Rejuvenator's tap activation.
• Rinoa, Angel Wing

  2W

  Legendary Creature — Human Rebel WarlockW

  Recursion engine: one card can reanimate repeatedly (an activated ability, or a return that comes back once a turn), and the other is a creature worth bringing back again and again — or a creature you recast from your graveyard beside a sacrifice outlet that doesn't pay for the recast. Real, repeatable value — not an infinite loop on its own.
• Out of the Tombs

  2B

  EnchantmentB

  Recursion engine: one card can reanimate repeatedly (an activated ability, or a return that comes back once a turn), and the other is a creature worth bringing back again and again — or a creature you recast from your graveyard beside a sacrifice outlet that doesn't pay for the recast. Real, repeatable value — not an infinite loop on its own.
• Illicit Masquerade

  3B

  EnchantmentB

  Graveyard pair: one card brings creatures back from the graveyard repeatedly (or a creature that returns itself), and the other keeps feeding the loop — a recurring reanimator with a payoff, or a sacrifice outlet with a self-recurring creature.
• White Plume Adventurer

  2W

  Creature — Orc ClericW

  White Plume Adventurer untaps all (or many) permanents, refreshing Rainveil Rejuvenator's tap activation.
• Avatar Kyoshi, Earthbender

  5GGG

  Legendary Creature — Human AvatarG

  Graveyard pair: one card brings creatures back from the graveyard repeatedly (or a creature that returns itself), and the other keeps feeding the loop — a recurring reanimator with a payoff, or a sacrifice outlet with a self-recurring creature.
• Chandra, Flameshaper

  5RR

  Legendary Planeswalker — ChandraR

  Copy engine: one card makes copies of a creature — once a turn, or once for each time you pay its cost — and each copy pays off: the creature's enter-the-battlefield effect fires again, or the hasty copy uses its tap ability. Real, repeatable value — every copy has its turn or its price, so it never goes infinite on its own.
• Recurring Nightmare

  2B

  EnchantmentB

  Recursion engine: one card can reanimate repeatedly (an activated ability, or a return that comes back once a turn), and the other is a creature worth bringing back again and again — or a creature you recast from your graveyard beside a sacrifice outlet that doesn't pay for the recast. Real, repeatable value — not an infinite loop on its own.
• The Mighty Thor, Jane Foster

  1WU

  Legendary Creature — Human God HeroUW

  Blink engine: one card blinks creatures — once a turn, once a combat, or each time you pay — and the other's enter-the-battlefield effect fires again on every blink. Real, repeatable value — never infinite on its own.
• Mirrorhall Mimic // Ghastly Mimicry

  3U

  Creature — Spirit // Enchantment — AuraU

  One-shot copy enabler: a card enters as a copy of another (Phantasmal Image, Body Double, Phyrexian Metamorph), firing the partner's substantive ETB once. Not a repeating chain — fires once on entry — but valuable when the partner's ETB is combo-grade (graveyard reanimator, mana doubler, etc.).
• Veteran Beastrider

  1GW

  Creature — Human KnightGW

  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.
• The Thirteenth Doctor

  1GU

  Legendary Creature — Time Lord DoctorGU

  The Thirteenth Doctor untaps all (or many) permanents, refreshing Rainveil Rejuvenator's tap activation.
• Hell's Caretaker

  3B

  Creature — HorrorB

  Recursion engine: one card can reanimate repeatedly (an activated ability, or a return that comes back once a turn), and the other is a creature worth bringing back again and again — or a creature you recast from your graveyard beside a sacrifice outlet that doesn't pay for the recast. Real, repeatable value — not an infinite loop on its own.
• Soulherder

  1WU

  Creature — SpiritUW

  Blink engine: one card blinks creatures — once a turn, once a combat, or each time you pay — and the other's enter-the-battlefield effect fires again on every blink. Real, repeatable value — never infinite on its own.
• Don & Leo, Problem Solvers

  3W/UW/U

  Legendary Creature — Mutant Ninja TurtleUW

  Blink engine: one card blinks creatures — once a turn, once a combat, or each time you pay — and the other's enter-the-battlefield effect fires again on every blink. Real, repeatable value — never infinite on its own.
• Drumbellower

  2W

  Creature — SpiritW

  Drumbellower untaps all (or many) permanents, refreshing Rainveil Rejuvenator's tap activation.
• Plargg, Dean of Chaos // Augusta, Dean of Order

  1R2W

  Legendary Creature — Orc Shaman // Legendary Creature — Human ClericRW

  Plargg, Dean of Chaos untaps all (or many) permanents, refreshing Rainveil Rejuvenator's tap activation.
• Jackdaw Savior

  2W

  Creature — Bird ClericW

  Graveyard pair: one card brings creatures back from the graveyard repeatedly (or a creature that returns itself), and the other keeps feeding the loop — a recurring reanimator with a payoff, or a sacrifice outlet with a self-recurring creature.
• Ezri Dax, Newly Joined

  1W

  Legendary Creature — Trill AdvisorW

  One-shot copy enabler: a card enters as a copy of another (Phantasmal Image, Body Double, Phyrexian Metamorph), firing the partner's substantive ETB once. Not a repeating chain — fires once on entry — but valuable when the partner's ETB is combo-grade (graveyard reanimator, mana doubler, etc.).
• Intellectual Offering

  4U

  InstantU

  Intellectual Offering untaps all (or many) permanents, refreshing Rainveil Rejuvenator's tap activation.
• Dazzling Theater // Prop Room

  3W2W

  Enchantment — Room // Enchantment — RoomW

  Dazzling Theater untaps all (or many) permanents, refreshing Rainveil Rejuvenator's tap activation.
• Athreos, Shroud-Veiled

  4WB

  Legendary Enchantment Creature — GodBW

  Graveyard pair: one card brings creatures back from the graveyard repeatedly (or a creature that returns itself), and the other keeps feeding the loop — a recurring reanimator with a payoff, or a sacrifice outlet with a self-recurring creature.
• The Legend of Yangchen // Avatar Yangchen

  3WW

  Enchantment — Saga // Legendary Creature — AvatarW

  Blink engine: one card blinks creatures — once a turn, once a combat, or each time you pay — and the other's enter-the-battlefield effect fires again on every blink. Real, repeatable value — never infinite on its own.