How can you create a combo with Riku of Two Reflections, Worldgorger Dragon?
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[START OF COMBO]This combo can be formed with Riku of Two Reflections, Worldgorger Dragon

Color identity: GUR
Mana cost: {3}{R}{R}{R}
Steps:
  1. Cast Worldgorger Dragon by paying {3}{R}{R}{R}.
  2. Worldgorger Dragon enters the battlefield, triggering its first ability and Riku's second ability.
  3. Holding priority, activate any number of permanents by tapping them, adding at least {1}{G}{U}.
  4. Resolve the Riku trigger, causing you to pay {G}{U} to create a token copy of Worldgorger Dragon.
  5. The token Worldgorger Dragon enters the battlefield, triggering its first ability, exiling all other permanents you control.
  6. The nontoken Worldgorger Dragon leaves the battlefield, triggering its second ability, returning nothing from exile to the battlefield.
  7. Resolve the Worldgorger Dragon trigger from step 2, exiling the token Worldgorger Dragon.
  8. The token Worldgorger Dragon leaves the battlefield, triggering its second ability, returning all permanents exiled with it to the battlefield.
  9. Repeat from step 2.[END OF COMBO STEPS]

Result:
  - Infinite blinking of permanents you control
  - Infinite enters the battlefield
  - Infinite leaves the battlefield
  - Infinite mana permanents you control can produce[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - Riku of Two Reflections must be on the battlefield
  - Worldgorger Dragon must be in your hand
  - You control any number of permanents that enter the battlefield untapped and can tap to produce at least {1}{G}{U}.
[END OF COMBO PREREQUISITES]
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