How can you create a combo with Goblin Welder, Retreat to Coralhelm, Seat of the Synod, Great Furnace?
user
[START OF COMBO]This combo can be formed with Goblin Welder, Retreat to Coralhelm, Seat of the Synod, Great Furnace

Color identity: UR
Mana cost: 
Steps:
  1. Activate Goblin Welder by tapping it, causing you to sacrifice Great Furnace and return Seat of the Synod from your graveyard to the battlefield.
  2. Seat of the Synod enters the battlefield, triggering Retreat to Coralhelm, untapping Goblin Welder.
  3. Activate Seat of the Synod by tapping it, adding {U}.
  4. Activate Goblin Welder by tapping it, causing you to sacrifice Seat of the Synod and return Great Furnace from your graveyard to the battlefield.
  5. Great Furnace enters the battlefield, triggering Retreat to Coralhelm, untapping Goblin Welder.
  6. Activate Great Furnace by tapping it, adding {R}.
  7. Repeat.[END OF COMBO STEPS]

Result:
  - Infinite blue mana
  - Infinite landfall triggers
  - Infinite red mana[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - Goblin Welder must be on the battlefield
  - Retreat to Coralhelm must be on the battlefield
  - Seat of the Synod must be in the graveyard
  - Great Furnace must be on the battlefield
  - Goblin Welder does not have summoning sickness.
[END OF COMBO PREREQUISITES]
assistant