How can you create a combo with Maralen of the Mornsong, Timestream Navigator, Batterskull, Concordant Crossroads?
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[START OF COMBO]This combo can be formed with Maralen of the Mornsong, Timestream Navigator, Batterskull, Concordant Crossroads

Color identity: BGU
Mana cost: {3}{U}{U}{U} each turn
Steps:
  1. At the beginning of your upkeep, Maralen triggers, causing you to lose three life and search your library for Timestream Navigator and put it into your hand.
  2. Cast Timestream Navigator by paying {1}{U}.
  3. If you don't have the city's blessing, Timestream Navigator triggers, causing you to get the city's blessing.
  4. Activate Timestream Navigator by paying {2}{U}{U}, tapping and putting it on the bottom of your library, causing you to take an extra turn after this one.
  5. Deal combat damage with Maralen, causing you to gain at least six life.
  6. Repeat each turn.[END OF COMBO STEPS]

Result:
  - Infinite turns[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - Maralen of the Mornsong must be on the battlefield
  - Timestream Navigator must be in the library
  - Batterskull must be on the battlefield
  - Concordant Crossroads must be on the battlefield
  - Batterskull attached to Maralen.
  - Your life total is at least four.
  - An opponent cannot block and kill Maralen.
  - You control nine permanents and/or have the city's blessing.
[END OF COMBO PREREQUISITES]
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