Gwenna, Eyes of Gaea, Cloudstone Curio, Grim Wanderer, and Sheltering Ancient

Prerequisites

• Gwenna, Eyes of Gaea on the battlefield
• Cloudstone Curio on the battlefield
• Grim Wanderer in hand
• Sheltering Ancient on the battlefield
• Gwenna does not have summoning sickness

Steps

1. Activate Gwenna by tapping it, adding that can only be spent to cast creature spells or activate abilities of creatures
2. Cast Grim Wanderer by paying
3. Gwenna triggers, putting a +1/+1 counter on it and untapping it
4. Grim Wanderer enters the battlefield, triggering Cloudstone Curio, returning Sheltering Ancient from the battlefield to your hand
5. Activate Gwenna by tapping it, adding that can only be spent to cast creature spells or activate abilities of creatures
6. Cast Sheltering Ancient by paying
7. Gwenna triggers, putting a +1/+1 counter on it and untapping it
8. Sheltering Ancient enters the battlefield, triggering Cloudstone Curio, returning Grim Wanderer from the battlefield to your hand
9. Repeat

Results

• Infinite +1/+1 counters on Gwenna
• Infinite ETB
• Infinite LTB
• Infinite storm count