Confidence:StrongSolidPlausibleTentativeSpeculative

• Sword of the Paruns✓

  4

  Artifact — EquipmentC

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Staff of Domination✓

  3

  ArtifactC

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Umbral Mantle✓

  3

  Artifact — EquipmentC

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Crab Umbra✓

  U

  Enchantment — AuraU

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Season of Growth

  1G

  EnchantmentG

  Both cards trigger when a creature enters the battlefield — they fire together.
• Spreading Plague

  4B

  EnchantmentB

  Both cards trigger when a creature enters the battlefield — they fire together.
• Tinybones Joins Up

  B

  Legendary EnchantmentB

  Both cards trigger when a creature enters the battlefield — they fire together.
• Faramir, Steward of Gondor

  1WU

  Legendary Creature — Human NobleUW

  Both cards trigger when a creature enters the battlefield — they fire together.
• Garruk, Curse Breaker

  3GG

  Legendary Planeswalker — GarrukG

  Both cards trigger when a creature enters the battlefield — they fire together.
• Kadena, Slinking Sorcerer

  1BGU

  Legendary Creature — Snake Wizard SorcererBGU

  Both cards trigger when a creature enters the battlefield — they fire together.
• Grist, Voracious Larva // Grist, the Plague Swarm

  G

  Legendary Creature — Insect // Legendary Planeswalker — GristBG

  Both cards trigger when a creature enters the battlefield — they fire together.
• Copperhorn Scout

  G

  Creature — Elf ScoutG

  Copperhorn Scout untaps all (or many) permanents, refreshing Heronblade Elite's tap activation.
• Warden of the Grove

  2G

  Creature — HydraG

  Both cards trigger when a creature enters the battlefield — they fire together.
• Momo, Friendly Flier

  W

  Legendary Creature — Lemur Bat AllyW

  Both cards trigger when a creature enters the battlefield — they fire together.
• Fire Lord Zuko

  RWB

  Legendary Creature — Human Noble AllyBRW

  Both cards trigger when a creature enters the battlefield — they fire together.
• Lagrella, the Magpie

  GWU

  Legendary Creature — Human SoldierGUW

  Both cards trigger when a creature enters the battlefield — they fire together.
• White Plume Adventurer

  2W

  Creature — Orc ClericW

  White Plume Adventurer untaps all (or many) permanents, refreshing Heronblade Elite's tap activation.
• The Sibsig Ceremony

  BBB

  Legendary EnchantmentB

  Both cards trigger when a creature enters the battlefield — they fire together.
• Prowl, Stoic Strategist // Prowl, Pursuit Vehicle

  3W

  Legendary Artifact Creature — Robot // Legendary Artifact — VehicleW

  Both cards trigger when a creature enters the battlefield — they fire together.
• Gladewalker Ritualist

  2G

  Creature — ShapeshifterG

  Both cards trigger when a creature enters the battlefield — they fire together.
• Lonis, Cryptozoologist

  GU

  Legendary Creature — Snake Elf ScoutGU

  Both cards trigger when a creature enters the battlefield — they fire together.
• Chandra, Flameshaper

  5RR

  Legendary Planeswalker — ChandraR

  Copy engine: one card makes copies of a creature — once a turn, or once for each time you pay its cost — and each copy pays off: the creature's enter-the-battlefield effect fires again, or the hasty copy uses its tap ability. Real, repeatable value — every copy has its turn or its price, so it never goes infinite on its own.
• Garruk's Uprising

  2G

  EnchantmentG

  Both cards trigger when a creature enters the battlefield — they fire together.
• April O'Neil, Live on the Scene

  1U

  Legendary Creature — Human DetectiveU

  Both cards trigger when a creature enters the battlefield — they fire together.
• Elesh Norn, Mother of Machines

  4W

  Legendary Creature — Phyrexian PraetorW

  Elesh Norn, Mother of Machines makes Heronblade Elite's triggered ability trigger an additional time — each time it fires, you get it twice. Value, not a loop.