Metalworker Combos
Metalworker + Cogwork Assembler
Metalworker + Umbral Mantle
Metalworker + Sword of the Paruns
Metalworker + Staff of Domination
Metalworker + Voltaic Construct
Urza, Prince of Kroog + Metalworker + Retreat to Coralhelm
Urza, Prince of Kroog + Metalworker + Lightning Greaves
Urza, Prince of Kroog + Metalworker + Akroma's Memorial
Urza, Prince of Kroog + Corridor Monitor + Metalworker
Urza, Lord High Artificer + Metalworker + Umbral Mantle
Combo result
Infinite colorless mana. Infinite blue mana. Cast any cards from your library with blue or colorless casting costs.
Prerequisites
All permanents on the battlefield. Metalworker is not summoning sick. Umbral Mantle equipped to Metalworker. You have at least 2 additional artifacts in hand.