Confidence:StrongSolidPlausibleTentativeSpeculative

• Roaming Throne

  4

  Artifact Creature — GolemC

  Roaming Throne makes Roiling Horror's triggered ability trigger an additional time — each time it fires, you get it twice. Value, not a loop.
• Mirror Room // Fractured Realm

  2U5UU

  Enchantment — Room // Enchantment — RoomU

  Mirror Room makes Roiling Horror's triggered ability trigger an additional time — each time it fires, you get it twice. Value, not a loop.
• Wizard's Staff

  1U

  Artifact — EquipmentU

  Wizard's Staff makes Roiling Horror's triggered ability trigger an additional time — each time it fires, you get it twice. Value, not a loop.
• Reanimate

  B

  SorceryB

  Reanimate puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Grave Researcher // Reanimate

  2BB

  Creature — Troll Warlock // SorceryB

  Grave Researcher puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Yore-Tiller Nephilim

  WUBR

  Creature — NephilimBRUW

  Yore-Tiller Nephilim puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Sefris of the Hidden Ways

  WUB

  Legendary Creature — Human WizardBUW

  Sefris of the Hidden Ways puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Recurring Nightmare

  2B

  EnchantmentB

  Recurring Nightmare puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Priest of Fell Rites

  WB

  Creature — Human WarlockBW

  Priest of Fell Rites puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Liliana, Waker of the Dead

  2BB

  Legendary Planeswalker — LilianaB

  Liliana, Waker of the Dead puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Animate Dead

  1B

  Enchantment — AuraB

  Animate Dead puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Exhume

  1B

  SorceryB

  Exhume puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Hell's Caretaker

  3B

  Creature — HorrorB

  Hell's Caretaker puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Life // Death

  G1B

  Sorcery // SorceryBG

  Life puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Kardur's Vicious Return

  2BR

  Enchantment — SagaBR

  Kardur's Vicious Return puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Dance of the Dead

  1B

  Enchantment — AuraB

  Dance of the Dead puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Meren of Clan Nel Toth

  2BG

  Legendary Creature — Human ShamanBG

  Meren of Clan Nel Toth puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Victimize

  2B

  SorceryB

  Victimize puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Persist

  1B

  SorceryB

  Persist puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Soul Exchange

  BB

  SorceryB

  Soul Exchange puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Ascent of the Worthy

  1WB

  Enchantment — SagaBW

  Ascent of the Worthy puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Rite of the Moth

  1WBB

  SorceryBW

  Rite of the Moth puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Soulcoil Viper

  2B

  Creature — SnakeB

  Soulcoil Viper puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Marshal's Anthem

  2WW

  EnchantmentW

  Marshal's Anthem puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Necromancy

  2B

  EnchantmentB

  Necromancy puts Roiling Horror onto the battlefield from a graveyard without casting it, so its mana cost is never paid.