Confidence:StrongSolidPlausibleTentativeSpeculative

• Origin of the Hidden Ones

  3R

  Enchantment — SagaR

  Both cards produce the same kind of effect (shared token subtype).
• The Eternal Wanderer

  4WW

  Legendary PlaneswalkerW

  The Eternal Wanderer blinks (exiles and returns) a permanent, re-firing Headsplitter's enter-the-battlefield effect.
• Jolted Awake

  W

  SorceryW

  Jolted Awake returns creatures from the graveyard to the battlefield, re-firing Headsplitter's enter-the-battlefield effect.
• Queen Marchesa

  1RWB

  Legendary Creature — Human AssassinBRW

  Both cards produce the same kind of effect (shared token subtype).
• Phelia, Exuberant Shepherd

  1W

  Legendary Creature — DogW

  Phelia, Exuberant Shepherd blinks (exiles and returns) a permanent, re-firing Headsplitter's enter-the-battlefield effect.
• Vraska the Unseen

  3BG

  Legendary Planeswalker — VraskaBG

  Both cards produce the same kind of effect (shared token subtype).
• Iridescent Vinelasher

  B

  Creature — Lizard AssassinB

  Both cards produce the same kind of effect (shared token subtype).
• Goblin Engineer

  1R

  Creature — Goblin ArtificerR

  Goblin Engineer returns creatures from the graveyard to the battlefield, re-firing Headsplitter's enter-the-battlefield effect.
• Explosive Getaway

  3RW

  SorceryRW

  Explosive Getaway blinks (exiles and returns) a permanent, re-firing Headsplitter's enter-the-battlefield effect.
• The Mighty Thor, Jane Foster

  1WU

  Legendary Creature — Human God HeroUW

  The Mighty Thor, Jane Foster blinks (exiles and returns) a permanent, re-firing Headsplitter's enter-the-battlefield effect.
• Aerial Extortionist

  3WW

  Creature — Bird SoldierW

  Aerial Extortionist exiles a permanent and lets its owner cast it again — the recast fires Headsplitter's cast trigger or its enter-the-battlefield effect.
• What Must Be Done

  3WW

  SorceryW

  What Must Be Done returns creatures from the graveyard to the battlefield, re-firing Headsplitter's enter-the-battlefield effect.
• The Mind Stone

  1W

  Legendary Artifact — Infinity StoneW

  The Mind Stone blinks (exiles and returns) a permanent, re-firing Headsplitter's enter-the-battlefield effect.
• Elrond, Moon-Reader

  2U

  Legendary Creature — Elf NobleU

  Elrond, Moon-Reader blinks (exiles and returns) a permanent, re-firing Headsplitter's enter-the-battlefield effect.
• Don & Leo, Problem Solvers

  3W/UW/U

  Legendary Creature — Mutant Ninja TurtleUW

  Don & Leo, Problem Solvers blinks (exiles and returns) a permanent, re-firing Headsplitter's enter-the-battlefield effect.
• Temporal Tribulation

  2U

  InstantU

  Temporal Tribulation blinks (exiles and returns) a permanent, re-firing Headsplitter's enter-the-battlefield effect.
• Recommission

  1W

  SorceryW

  Recommission returns creatures from the graveyard to the battlefield, re-firing Headsplitter's enter-the-battlefield effect.
• Goblin Welder

  R

  Creature — Goblin ArtificerR

  Goblin Welder returns creatures from the graveyard to the battlefield, re-firing Headsplitter's enter-the-battlefield effect.
• Nahiri's Resolve

  3RW

  EnchantmentRW

  Nahiri's Resolve blinks (exiles and returns) a permanent, re-firing Headsplitter's enter-the-battlefield effect.
• Tameshi, Reality Architect

  2U

  Legendary Creature — Moonfolk WizardUW

  Tameshi, Reality Architect returns creatures from the graveyard to the battlefield, re-firing Headsplitter's enter-the-battlefield effect.
• Lorehold Charm

  RW

  InstantRW

  Lorehold Charm returns creatures from the graveyard to the battlefield, re-firing Headsplitter's enter-the-battlefield effect.
• The Legend of Yangchen // Avatar Yangchen

  3WW

  Enchantment — Saga // Legendary Creature — AvatarW

  The Legend of Yangchen exiles a permanent and lets its owner cast it again — the recast fires Headsplitter's cast trigger or its enter-the-battlefield effect.
• Aya of Alexandria

  2RW

  Legendary Creature — Human AssassinRW

  Both cards produce the same kind of effect (shared token subtype).
• Soul Partition

  1W

  InstantW

  Soul Partition exiles a permanent and lets its owner cast it again — the recast fires Headsplitter's cast trigger or its enter-the-battlefield effect.
• Appa, Steadfast Guardian

  2WW

  Legendary Creature — Bison AllyW

  Appa, Steadfast Guardian exiles a permanent and lets its owner cast it again — the recast fires Headsplitter's cast trigger or its enter-the-battlefield effect.