Confidence:StrongSolidPlausibleTentativeSpeculative

• 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.
• Summoner's Sending

  1W

  EnchantmentW

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

  1GGGG

  SorceryG

  Both cards produce the same kind of effect (shared token subtype).
• Tezzeret, Cruel Captain

  3

  Legendary Planeswalker — TezzeretC

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

  GWU

  Legendary Creature — Human SoldierGUW

  Both cards trigger when a creature enters the battlefield — they fire together.
• Terra, Magical Adept // Esper Terra

  1RG

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

  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.
• April O'Neil, Live on the Scene

  1U

  Legendary Creature — Human DetectiveU

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

  1G

  Creature — Elf ArtificerG

  Both cards trigger when a creature enters the battlefield — they fire together.
• Archon of Sun's Grace

  2WW

  Creature — ArchonW

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

  5BB

  Creature — Dragon HorrorB

  Both cards trigger when a creature enters the battlefield — they fire together.
• Prowl, Stoic Strategist // Prowl, Pursuit Vehicle

  3W

  Legendary Artifact Creature — Robot // Legendary Artifact — VehicleW

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

  2WUB

  Legendary Creature — Astartes WarriorBUW

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

  1G

  Creature — Human Artificer ScoutG

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

  1

  ArtifactC

  Both cards trigger when a creature enters the battlefield — they fire together.
• Killian, Decisive Mentor

  1WB

  Legendary Creature — Human WarlockBW

  Both cards trigger when a creature enters the battlefield — they fire together.
• The Mighty Thor, Jane Foster

  1WU

  Legendary Creature — Human God HeroUW

  Both cards trigger when a creature enters the battlefield — they fire together.
• Antiquities on the Loose

  1WW

  SorceryW

  Both cards produce the same kind of effect (shared token subtype).
• Tetzin, Gnome Champion // The Golden-Gear Colossus

  URW

  Legendary Artifact Creature — Gnome // Legendary Artifact Creature — GnomeRUW

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

  2U

  Creature — Human ScoutU

  Both cards trigger when a creature enters the battlefield — they fire together.
• Losheel, Clockwork Scholar

  2W

  Legendary Creature — Elephant ArtificerW

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

  2

  Artifact — BookC

  Both cards trigger when a creature enters the battlefield — they fire together.
• Kykar, Wind's Fury

  1URW

  Legendary Creature — Bird WizardRUW

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

  1

  Artifact — EquipmentC

  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.).
• Mister Fantastic, Reed Richards

  3U

  Legendary Creature — Human Scientist HeroU

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

  1GW

  Legendary Creature — Halfling AdvisorGW

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