How can you create a combo with Rootha, Mercurial Artist, Mana Echoes, Sram's Expertise?
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[START OF COMBO]This combo can be formed with Rootha, Mercurial Artist, Mana Echoes, Sram's Expertise

Color identity: URW
Mana cost: {4}{W}{W}
Steps:
  1. Cast Sram's Expertise by paying {2}{W}{W}.
  2. Holding priority, activate Rootha by paying {2} and returning it to your hand, copying Sram's Expertise.
  3. Resolve the copy of Sram's Expertise, creating three 1/1 Servo artifact creature tokens and casting Rootha without paying its mana cost.
  4. When the Servos and Rootha enters the battlefield, Mana Echoes triggers four times, adding {C}{C}{C} for each Servo you control, plus {C} for each Orc and/or Shaman you control.
  5. Repeat from step 2.[END OF COMBO STEPS]

Result:
  - Infinite colorless mana
  - Infinite enters the battlefield
  - Infinite leaves the battlefield
  - Infinite magecraft triggers
  - Infinite storm count[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - Rootha, Mercurial Artist must be on the battlefield
  - Mana Echoes must be on the battlefield
  - Sram's Expertise must be in your hand
[END OF COMBO PREREQUISITES]
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