Confidence:StrongSolidPlausibleTentativeSpeculative

• The Rise of Sozin // Fire Lord Sozin

  4BB

  Enchantment — Saga // Legendary Creature — Human NobleB

  Draw pair: both cards engage with card draw. With a damage-or-draw trigger between them they form a draw engine.
• 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.
• 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.
• Archon of Sun's Grace

  2WW

  Creature — ArchonW

  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.
• Killian, Decisive Mentor

  1WB

  Legendary Creature — Human WarlockBW

  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.
• 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.).
• Romana II

  3W

  Legendary Creature — Time Lord ScientistW

  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.
• Ghostly Dancers

  3WW

  Creature — SpiritW

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

  U

  Creature — Crab SkeletonU

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

  1UB

  Enchantment Creature — NightmareBU

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

  G

  Creature — Elf RangerG

  Both cards trigger when a creature enters the battlefield — they fire together.
• Yoshimaru, Ever Faithful

  W

  Legendary Creature — DogW

  Both cards trigger when a creature enters the battlefield — they fire together.
• Invasion of Theros // Ephara, Ever-Sheltering

  2W

  Battle — Siege // Legendary Enchantment Creature — GodUW

  Both cards trigger when a creature enters the battlefield — they fire together.
• Threats Around Every Corner

  3G

  EnchantmentG

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

  WU

  Creature — Human ScoutUW

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

  2G

  Creature — Human WarriorG

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

  GW

  InstantGW

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

  1B

  Creature — LeechB

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

  3UU

  Legendary Snow Creature — YetiGUW

  Both cards trigger when a creature enters the battlefield — they fire together.
• Fire Lord Zuko

  RWB

  Legendary Creature — Human Noble AllyBRW

  Both cards trigger when a creature enters the battlefield — they fire together.
• Baron Bertram Graywater

  2WB

  Legendary Creature — Vampire NobleBW

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