Confidence:StrongSolidPlausibleTentativeSpeculative

• 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.
• 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.
• Cacophodon

  3G

  Creature — DinosaurG

  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.
• Chevill, Bane of Monsters

  BG

  Legendary Creature — Human RogueBG

  Clockwork Hydra produces damage that can kill creatures, enabling Chevill, Bane of Monsters's death-trigger or removal payoff.
• Minsc & Boo, Timeless Heroes

  2RG

  Legendary Planeswalker — MinscGR

  Clockwork Hydra produces damage that can kill creatures, enabling Minsc & Boo, Timeless Heroes's death-trigger or removal payoff.
• The Meathook Massacre

  XBB

  Legendary EnchantmentB

  Clockwork Hydra produces damage that can kill creatures, enabling The Meathook Massacre's death-trigger or removal payoff.
• Mari, the Killing Quill

  1BB

  Legendary Creature — Vampire AssassinB

  Clockwork Hydra produces damage that can kill creatures, enabling Mari, the Killing Quill's death-trigger or removal payoff.
• Quest for the Gravelord

  B

  EnchantmentB

  Clockwork 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

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

  1BG

  Legendary Creature — Human Warrior VillainBG

  Clockwork Hydra produces damage that can kill creatures, enabling Kraven the Hunter's death-trigger or removal payoff.
• 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.
• Lita, Mechanical Engineer

  2W

  Legendary Artifact Creature — ArtificerW

  Lita, Mechanical Engineer untaps all (or many) permanents, refreshing Clockwork Hydra's tap activation.
• Toshiro Umezawa

  1BB

  Legendary Creature — Human SamuraiB

  Clockwork 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 Clockwork Hydra's tap activation.
• Malicious Affliction

  BB

  InstantB

  Clockwork 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

  Clockwork 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

  Clockwork 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 Clockwork Hydra's tap activation.
• Emeritus of Woe // Demonic Tutor

  3B1B

  Creature — Vampire Warlock // SorceryB

  Clockwork Hydra produces damage that can kill creatures, enabling Emeritus of Woe's death-trigger or removal payoff.
• Skullclamp

  1

  Artifact — EquipmentC

  Clockwork Hydra produces damage that can kill creatures, enabling Skullclamp's death-trigger or removal payoff.
• Jace, Ingenious Mind-Mage

  4UU

  Legendary Planeswalker — JaceU

  Jace, Ingenious Mind-Mage untaps all (or many) permanents, refreshing Clockwork Hydra's tap activation.
• Lagomos, Hand of Hatred

  1BR

  Legendary Creature — Human ShamanBR

  Clockwork Hydra produces damage that can kill creatures, enabling Lagomos, Hand of Hatred's death-trigger or removal payoff.
• Ob Nixilis, Unshackled

  4BB

  Legendary Creature — DemonB

  Clockwork Hydra produces damage that can kill creatures, enabling Ob Nixilis, Unshackled's death-trigger or removal payoff.