Confidence:StrongSolidPlausibleTentativeSpeculative

• Delney, Streetwise Lookout

  2W

  Legendary Creature — Human ScoutW

  Delney, Streetwise Lookout makes Plague Fiend's triggered ability trigger an additional time — each time it fires, you get it twice. Value, not a loop.
• Roaming Throne

  4

  Artifact Creature — GolemC

  Roaming Throne makes Plague Fiend'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 Plague Fiend'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 Plague Fiend's triggered ability trigger an additional time — each time it fires, you get it twice. Value, not a loop.
• Sygg, Wanderwine Wisdom // Sygg, Wanderbrine Shield

  1U

  Legendary Creature — Merfolk Wizard // Legendary Creature — Merfolk RogueUW

  Both cards trigger on damage dealt — they fire together.
• Reanimate

  B

  SorceryB

  Reanimate puts Plague Fiend onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Helping Hand

  W

  SorceryW

  Helping Hand puts Plague Fiend onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Unearth

  B

  SorceryB

  Unearth puts Plague Fiend onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• Fblthp, Impossibly Lost

  1U

  Legendary Creature — HomunculusU

  Both cards trigger on damage dealt — they fire together.
• Grave Researcher // Reanimate

  2BB

  Creature — Troll Warlock // SorceryB

  Grave Researcher puts Plague Fiend onto the battlefield from a graveyard without casting it, so its mana cost is never paid.
• The Beast, Deathless Prince

  2BR

  Legendary Creature — DemonBR

  Both cards trigger on damage dealt — they fire together.
• Vraska the Unseen

  3BG

  Legendary Planeswalker — VraskaBG

  Both cards trigger on damage dealt — they fire together.
• Cryoshatter

  U

  Enchantment — AuraU

  Both cards trigger on damage dealt — they fire together.
• Sleep Magic

  U

  Enchantment — AuraU

  Both cards trigger on damage dealt — they fire together.
• Lost Jitte

  1

  Legendary Artifact — EquipmentC

  Both cards trigger on damage dealt — they fire together.
• Puppet Master, String Puller

  2R

  Legendary Creature — Human Artificer VillainR

  Both cards trigger on damage dealt — they fire together.
• All-Out Assault

  2RWB

  EnchantmentBRW

  All-Out Assault grants an extra combat phase, enabling Plague Fiend's combat-trigger payoff.
• Witch-king of Angmar

  3BB

  Legendary Creature — Wraith NobleB

  Both cards trigger on damage dealt — they fire together.
• Sporogenic Infection

  1B

  Enchantment — AuraB

  Both cards trigger on damage dealt — they fire together.
• Cracked Skull

  2B

  Enchantment — AuraB

  Both cards trigger on damage dealt — they fire together.
• Frozen Solid

  1UU

  Enchantment — AuraU

  Both cards trigger on damage dealt — they fire together.
• The Aetherspark

  4

  Legendary Artifact Planeswalker — EquipmentC

  Both cards trigger on damage dealt — they fire together.
• Mire Blight

  B

  Enchantment — AuraB

  Both cards trigger on damage dealt — they fire together.
• Starscream, Power Hungry // Starscream, Seeker Leader

  3B

  Legendary Artifact Creature — Robot // Legendary Artifact — VehicleB

  Both cards trigger on damage dealt — they fire together.
• Arcbond

  2R

  InstantR

  Both cards trigger on damage dealt — they fire together.