Confidence:StrongSolidPlausibleTentativeSpeculative

• Lavabrink Floodgates

  3R

  ArtifactR

  Lavabrink Floodgates deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Hammerfist Giant

  4RR

  Creature — Giant WarriorR

  Hammerfist Giant deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Dragonback Assault

  3GUR

  EnchantmentGRU

  Dragonback Assault deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Flames of the Raze-Boar

  5R

  InstantR

  Flames of the Raze-Boar deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Omnath, Locus of Creation

  RGWU

  Legendary Creature — ElementalGRUW

  Omnath, Locus of Creation deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Incendiary Command

  3RR

  SorceryR

  Incendiary Command deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Radiating Lightning

  3R

  InstantR

  Radiating Lightning deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Flame Blitz

  R

  EnchantmentR

  Flame Blitz deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Bruce Banner // The Incredible Hulk

  U2RRGG

  Legendary Creature — Human Scientist Hero // Legendary Creature — Gamma Berserker HeroGRU

  Bruce Banner grants an extra combat phase, enabling Protean Hydra's combat-trigger payoff.
• Planetary Annihilation

  3RR

  SorceryR

  Planetary Annihilation deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Megaton's Fate

  5R

  SorceryR

  Megaton's Fate deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Glóin the Mighty // Easy Pickings

  3R2R

  Legendary Creature — Dwarf Warrior // Sorcery — AdventureR

  Glóin the Mighty deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Hour of Devastation

  3RR

  SorceryR

  Hour of Devastation deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Reckless Blaze

  3RR

  Sorcery — LessonR

  Reckless Blaze deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Splatter Technique

  1UURR

  SorceryRU

  Splatter Technique deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• All-Out Assault

  2RWB

  EnchantmentBRW

  All-Out Assault grants an extra combat phase, enabling Protean Hydra's combat-trigger payoff.
• Aggravated Assault

  2R

  EnchantmentR

  Aggravated Assault grants an extra combat phase, enabling Protean Hydra's combat-trigger payoff.
• Chandra, Flamecaller

  4RR

  Legendary Planeswalker — ChandraR

  Chandra, Flamecaller deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Mila, Crafty Companion // Lukka, Wayward Bonder

  1WW4RR

  Legendary Creature — Fox // Legendary Planeswalker — LukkaRW

  Mila, Crafty Companion produces broad damage that redirects through Protean Hydra into something useful.
• Star of Extinction

  5RR

  SorceryR

  Star of Extinction deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Fires of Mount Doom

  2R

  Legendary EnchantmentR

  Fires of Mount Doom produces broad damage that redirects through Protean Hydra into something useful.
• Burn Down the House

  3RR

  SorceryR

  Burn Down the House deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Urabrask // The Great Work

  2RR

  Legendary Creature — Phyrexian Praetor // Enchantment — SagaR

  Urabrask deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Calamity of Cinders

  5RR

  SorceryR

  Calamity of Cinders deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.
• Avengers: Under Siege

  2BR

  Enchantment — SagaBR

  Avengers: Under Siege deals damage to many targets, fueling Protean Hydra's damage-payoff trigger.