Confidence:StrongSolidPlausibleTentativeSpeculative

• Innkeeper's Talent

  1G

  Enchantment — ClassG

  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.
• Hexavus

  6

  Artifact Creature — ConstructC

  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.
• Roaming Throne

  4

  Artifact Creature — GolemC

  Roaming Throne makes Feral Thallid'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 Feral Thallid'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 Feral Thallid's triggered ability trigger an additional time — each time it fires, you get it twice. Value, not a loop.
• Reanimate

  B

  SorceryB

  Reanimate puts Feral Thallid 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 Feral Thallid onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Liliana, Death's Majesty

  3BB

  Legendary Planeswalker — LilianaB

  Liliana, Death's Majesty puts Feral Thallid 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 Feral Thallid 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 Feral Thallid onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Recurring Nightmare

  2B

  EnchantmentB

  Recurring Nightmare puts Feral Thallid onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Unfinished Business

  3WW

  SorceryW

  Unfinished Business puts Feral Thallid 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 Feral Thallid onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• The Cruelty of Gix

  3BB

  Enchantment — SagaB

  The Cruelty of Gix puts Feral Thallid 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 Feral Thallid onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Animate Dead

  1B

  Enchantment — AuraB

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

  1B

  SorceryB

  Exhume puts Feral Thallid 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 Feral Thallid onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Archpriest of Shadows

  3BB

  Creature — Human WarlockB

  Archpriest of Shadows puts Feral Thallid onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Life // Death

  G1B

  Sorcery // SorceryBG

  Life puts Feral Thallid onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Elrond, Moon-Reader

  2U

  Legendary Creature — Elf NobleU

  Feral Thallid has activated abilities that aren't mana abilities, fueling Elrond, Moon-Reader's activation-trigger.
• Kardur's Vicious Return

  2BR

  Enchantment — SagaBR

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

  2B

  SorceryB

  Victimize puts Feral Thallid onto the battlefield from a graveyard without casting it, so its mana cost is never paid.