Confidence:StrongSolidPlausibleTentativeSpeculative

• Fractal Harness

  X2G

  Artifact — EquipmentG

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• Study the Classics

  2G

  SorceryG

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• 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.
• Runaway Steam-Kin

  1R

  Creature — ElementalR

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• Brigone, Soldier of Meletis

  1W

  Legendary Creature — Human SoldierW

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• Chandra, Flameshaper

  5RR

  Legendary Planeswalker — ChandraR

  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.
• Sage of Hours

  1U

  Creature — Human WizardU

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• The Duke, Rebel Sentry

  W

  Legendary Creature — Human Rebel AllyW

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• Court of Garenbrig

  1GG

  EnchantmentG

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• Ramos, Dragon Engine

  6

  Legendary Artifact Creature — DragonBGRUW

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• Karlov of the Ghost Council

  WB

  Legendary Creature — Spirit AdvisorBW

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• Catti-brie of Mithral Hall

  GW

  Legendary Creature — Human ArcherGW

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• Etched Oracle

  4

  Artifact Creature — WizardC

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• Nephalia Smuggler

  U

  Creature — Human RogueU

  Blink pair: one card can blink creatures repeatedly, and the other's ETB rewards every re-entry. Free-running only when the blink is free or refunded (Deadeye + Drake class); otherwise a repeatable value engine.
• Soulherder

  1WU

  Creature — SpiritUW

  Blink pair: one card can blink creatures repeatedly, and the other's ETB rewards every re-entry. Free-running only when the blink is free or refunded (Deadeye + Drake class); otherwise a repeatable value engine.
• The Mind Stone

  1W

  Legendary Artifact — Infinity StoneW

  Blink pair: one card can blink creatures repeatedly, and the other's ETB rewards every re-entry. Free-running only when the blink is free or refunded (Deadeye + Drake class); otherwise a repeatable value engine.
• Gwen Stacy // Ghost-Spider

  1R2URW

  Legendary Creature — Human Performer Hero // Legendary Creature — Spider Human HeroRUW

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• Shinewend

  1W

  Creature — ElementalW

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• District Mascot

  G

  Creature — Dog MountG

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• Hollowmurk Siege

  BG

  EnchantmentBG

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• Saheeli Rai

  1UR

  Legendary Planeswalker — SaheeliRU

  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.
• Monoskelion

  2

  Artifact Creature — ConstructC

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• Haruspex

  3G

  Creature — TyranidG

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• Chamber Sentry

  X

  Artifact Creature — ConstructBGRUW

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.
• Sisterhood of Karn

  1G

  Creature — ClericG

  Counter synergy: both cards work with the same kind of counters, so their effects stack in a counters deck. Not necessarily a closed loop on its own.