Rootha, Mercurial Artist, Mana Echoes, and Sram's Expertise

Prerequisites

• Rootha, Mercurial Artist on the battlefield
• Mana Echoes on the battlefield
• Sram's Expertise in hand
• available

Steps

1. Cast Sram's Expertise by paying
2. Holding priority, activate Rootha by paying 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 for each Servo you control, plus for each Orc and/or Shaman you control
5. Repeat from step 2

Results

• Infinite colorless mana
• Infinite ETB
• Infinite LTB
• Infinite magecraft triggers
• Infinite storm count