Confidence:StrongSolidPlausibleTentativeSpeculative

• Riku of Many Paths

  GUR

  Legendary Creature — Human WizardGRU

  Both cards produce the same kind of effect (shared token subtype).
• Baron Helmut Zemo

  BBB

  Legendary Creature — Human Noble VillainB

  Copy engine: one card makes a copy of a creature every turn, and the other's enter-the-battlefield effect rewards each copy. Real, repeatable value — the partner can't untap or re-enter the copier, so it never goes infinite.
• Perch Protection

  4WW

  InstantW

  Both cards produce the same kind of effect (shared token subtype).
• Feroz, Ulgrotha's Warden

  3GWU

  Legendary Planeswalker — FerozGUW

  Both cards produce the same kind of effect (shared token subtype).
• Sidequest: Raise a Chocobo // Black Chocobo

  1G

  Enchantment // Creature — BirdG

  Both cards produce the same kind of effect (shared token subtype).
• Mu Yanling, Sky Dancer

  1UU

  Legendary Planeswalker — YanlingU

  Both cards produce the same kind of effect (shared token subtype).
• The Eagles Are Coming!

  1W

  InstantW

  Both cards produce the same kind of effect (shared token subtype).
• Murmuration

  4W

  EnchantmentW

  Both cards produce the same kind of effect (shared token subtype).
• Hermes, Overseer of Elpis

  3U

  Legendary Creature — Elder WizardU

  Both cards produce the same kind of effect (shared token subtype).
• Alrund's Epiphany

  5UU

  SorceryU

  Both cards produce the same kind of effect (shared token subtype).
• 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.).
• Love Song of Night and Day

  2W

  Enchantment — SagaW

  Both cards produce the same kind of effect (shared token subtype).
• The Raven Man

  1B

  Legendary Creature — Human WizardB

  Both cards produce the same kind of effect (shared token subtype).
• Emeria Angel

  2WW

  Creature — AngelW

  Both cards produce the same kind of effect (shared token subtype).
• Dovescape

  3W/UW/UW/U

  EnchantmentUW

  Both cards produce the same kind of effect (shared token subtype).
• Murmuring Mystic

  3U

  Creature — Human WizardU

  Both cards produce the same kind of effect (shared token subtype).
• Radagast, Wizard of Wilds

  2GU

  Legendary Creature — Avatar WizardGU

  Both cards produce the same kind of effect (shared token subtype).
• Migratory Route

  3WU

  SorceryUW

  Both cards produce the same kind of effect (shared token subtype).
• Falcon and Redwing

  2W

  Legendary Creature — Human Bird HeroW

  Both cards produce the same kind of effect (shared token subtype).
• Gysahl Greens

  1G

  SorceryG

  Both cards produce the same kind of effect (shared token subtype).
• Dino DNA

  1

  ArtifactC

  Copy engine: one card makes a copy of a creature every turn, and the other's enter-the-battlefield effect rewards each copy. Real, repeatable value — the partner can't untap or re-enter the copier, so it never goes infinite.
• Aven Wind Guide

  2WU

  Creature — Bird WarriorUW

  Both cards produce the same kind of effect (shared token subtype).
• Song of Eärendil

  3GU

  Enchantment — SagaGU

  Both cards produce the same kind of effect (shared token subtype).
• Chocobo Racetrack

  3GG

  ArtifactG

  Both cards produce the same kind of effect (shared token subtype).
• Cursed Mirror

  2R

  ArtifactR

  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.).