Confidence:StrongSolidPlausibleTentativeSpeculative

• Umbral Mantle✓

  3

  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.
• Sword of the Paruns✓

  4

  Artifact — EquipmentC

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

  4

  Artifact Creature — Golem ConstructC

  Untap loop: each side can untap what the other taps — a genuine mutual refresh engine.
• Lita, Mechanical Engineer

  2W

  Legendary Artifact Creature — ArtificerW

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• Copperhorn Scout

  G

  Creature — Elf ScoutG

  Copperhorn Scout untaps all (or many) permanents, refreshing Metalworker's tap activation.
• White Plume Adventurer

  2W

  Creature — Orc ClericW

  White Plume Adventurer untaps all (or many) permanents, refreshing Metalworker's tap activation.
• Jace, Ingenious Mind-Mage

  4UU

  Legendary Planeswalker — JaceU

  Jace, Ingenious Mind-Mage untaps all (or many) permanents, refreshing Metalworker's tap activation.
• Aggravated Assault

  2R

  EnchantmentR

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• Veteran Beastrider

  1GW

  Creature — Human KnightGW

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• The Thirteenth Doctor

  1GU

  Legendary Creature — Time Lord DoctorGU

  The Thirteenth Doctor untaps all (or many) permanents, refreshing Metalworker's tap activation.
• The Moment

  2

  Legendary ArtifactC

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• Intruder Alarm

  2U

  EnchantmentU

  Intruder Alarm untaps all (or many) permanents, refreshing Metalworker's tap activation.
• Drumbellower

  2W

  Creature — SpiritW

  Drumbellower untaps all (or many) permanents, refreshing Metalworker's tap activation.
• Gideon, Martial Paragon

  4W

  Legendary Planeswalker — GideonW

  Gideon, Martial Paragon untaps all (or many) permanents, refreshing Metalworker's tap activation.
• Voltaic Key

  1

  ArtifactC

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• Saryth, the Viper's Fang

  2GG

  Legendary Creature — Human WarlockG

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• Dazzling Theater // Prop Room

  3W2W

  Enchantment — Room // Enchantment — RoomW

  Dazzling Theater untaps all (or many) permanents, refreshing Metalworker's tap activation.
• Intellectual Offering

  4U

  InstantU

  Intellectual Offering untaps all (or many) permanents, refreshing Metalworker's tap activation.
• Stonybrook Angler

  1U

  Creature — Merfolk WizardU

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.
• Prophet of Kruphix

  3GU

  Creature — Human WizardGU

  Prophet of Kruphix untaps all (or many) permanents, refreshing Metalworker's tap activation.
• Éomer, Marshal of Rohan

  2RR

  Legendary Creature — Human KnightR

  Éomer, Marshal of Rohan untaps all (or many) permanents, refreshing Metalworker's tap activation.
• Ivorytusk Fortress

  2WBG

  Creature — ElephantBGW

  Ivorytusk Fortress untaps all (or many) permanents, refreshing Metalworker's tap activation.
• Unstoppable Plan

  2U

  EnchantmentU

  Unstoppable Plan untaps all (or many) permanents, refreshing Metalworker's tap activation.
• Thassa's Ire

  U

  EnchantmentU

  One-directional refresh: one card can untap permanents the other wants to reuse. Not self-sustaining on its own — the untapper has to keep showing up.