How can you create a combo with Turnabout, Twincast, Izzet Guildmage?
user
[START OF COMBO]This combo can be formed with Turnabout, Twincast, Izzet Guildmage

Color identity: UR
Mana cost: {4}{U}{U}{U}{U}{U}
Steps:
  1. Cast Turnabout for {2}{U}{U}.
  2. In response, Cast Twincast targeting Turnabout for {U}{U}.
  3. In response, Activate Izzet Guildmage's ability for {2}{U} targeting Twincast.
  4. Resolve the Izzet Guildmage's activated ability to copy Twincast targeting Turnabout with the copy of Twincast.
  5. Resolve the copy of Turnabout, created by the copy of Twincast to untap your lands that can produce at least {3}{U}.
  6. Repeat.[END OF COMBO STEPS]

Result:
  - Infinite colored mana
  - Infinite colorless mana[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - Turnabout must be in your hand
  - Twincast must be in your hand
  - Izzet Guildmage must be on the battlefield
  - Lands that produce {3}{U} on the battlefield.
[END OF COMBO PREREQUISITES]
assistant