How can you create a combo with Riku of Two Reflections, Narset's Reversal, Beacon of Tomorrows?
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[START OF COMBO]This combo can be formed with Riku of Two Reflections, Narset's Reversal, Beacon of Tomorrows

Color identity: GUR
Mana cost: {6}{U}{U}{U}{U}{U}{R} each turn
Steps:
  1. Cast Beacon of Tomorrows by paying {6}{U}{U}.
  2. Riku's first ability triggers - choose not to pay.
  3. Holding priority, cast Narset's Reversal by paying {U}{U}, targeting Beacon of Tomorrows.
  4. Riku's first ability triggers, causing you to pay {U}{R} to copy Narset's Reversal, with the copy targeting the original Narset's Reversal.
  5. Resolve the copy of Narset's Reversal, copying the original Narset's Reversal targeting Beacon of Tomorrows, and returning the original Narset's Reversal to your hand.
  6. Resolve the copy of Narset's Reversal created in step 5, copying Beacon of Tomorrows and returning the original Beacon of Tomorrows to your hand.
  7. Resolve Beacon of Tomorrows, causing you to take an extra turn after this one.
  8. Repeat each turn.[END OF COMBO STEPS]

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

Other prerequisites:
  - Riku of Two Reflections must be on the battlefield
  - Narset's Reversal must be in your hand
  - Beacon of Tomorrows must be in your hand
[END OF COMBO PREREQUISITES]
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