Confidence:StrongSolidPlausibleTentativeSpeculative

• Heliod, Sun-Crowned

  2W

  Legendary Enchantment Creature — GodW

  Counter + damage loop: one card spends counters to deal damage while the other replaces them on a hit (Heliod + Walking Ballista class).
• Najeela, the Blade-Blossom

  2R

  Legendary Creature — Human WarriorBGRUW

  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 Destined White Mage

  2W

  Legendary Creature — Human ClericW

  Counter + damage loop: one card spends counters to deal damage while the other replaces them on a hit (Heliod + Walking Ballista class).
• Vigor

  3GGG

  Creature — Elemental IncarnationG

  Counter + damage loop: one card spends counters to deal damage while the other replaces them on a hit (Heliod + Walking Ballista class).
• Esper Sojourners

  WUB

  Artifact Creature — Vedalken WizardBUW

  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.
• Thornbite Staff

  2

  Kindred Artifact — Shaman EquipmentC

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Panther Habit

  4

  Artifact — EquipmentC

  Counter + damage loop: one card spends counters to deal damage while the other replaces them on a hit (Heliod + Walking Ballista class).
• Heart-Shaped Herb

  4

  ArtifactC

  Counter + damage loop: one card spends counters to deal damage while the other replaces them on a hit (Heliod + Walking Ballista class).
• Bretagard Stronghold

  LandGW

  Counter + damage loop: one card spends counters to deal damage while the other replaces them on a hit (Heliod + Walking Ballista class).
• Chevill, Bane of Monsters

  BG

  Legendary Creature — Human RogueBG

  Molten Hydra produces damage that can kill creatures, enabling Chevill, Bane of Monsters's death-trigger or removal payoff.
• Banon, the Returners' Leader

  RW

  Legendary Creature — Human Cleric RebelRW

  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 Meathook Massacre

  XBB

  Legendary EnchantmentB

  Molten Hydra produces damage that can kill creatures, enabling The Meathook Massacre's death-trigger or removal payoff.
• Quest for the Gravelord

  B

  EnchantmentB

  Molten Hydra produces damage that can kill creatures, enabling Quest for the Gravelord's death-trigger or removal payoff.
• Gravecrawler

  B

  Creature — ZombieB

  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.
• Bequeathal

  G

  Enchantment — AuraG

  Molten Hydra produces damage that can kill creatures, enabling Bequeathal's death-trigger or removal payoff.
• Kraven the Hunter

  1BG

  Legendary Creature — Human Warrior VillainBG

  Molten Hydra produces damage that can kill creatures, enabling Kraven the Hunter's death-trigger or removal payoff.
• 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.
• Undead Sprinter

  BR

  Creature — ZombieBR

  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.
• Toshiro Umezawa

  1BB

  Legendary Creature — Human SamuraiB

  Molten Hydra produces damage that can kill creatures, enabling Toshiro Umezawa's death-trigger or removal payoff.
• Copperhorn Scout

  G

  Creature — Elf ScoutG

  Copperhorn Scout untaps all (or many) permanents, refreshing Molten Hydra's tap activation.
• Malicious Affliction

  BB

  InstantB

  Molten Hydra produces damage that can kill creatures, enabling Malicious Affliction's death-trigger or removal payoff.
• Timeline Culler

  BB

  Creature — Drix WarlockB

  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.
• Enduring Renewal

  2WW

  EnchantmentW

  Molten Hydra produces damage that can kill creatures, enabling Enduring Renewal's death-trigger or removal payoff.
• Glissa, the Traitor

  BGG

  Legendary Creature — Phyrexian Zombie ElfBG

  Molten Hydra produces damage that can kill creatures, enabling Glissa, the Traitor's death-trigger or removal payoff.
• White Plume Adventurer

  2W

  Creature — Orc ClericW

  White Plume Adventurer untaps all (or many) permanents, refreshing Molten Hydra's tap activation.