Gwenna, Eyes of Gaea, Temur Sabertooth, Phyrexian Dreadnought, and Training Grounds

Prerequisites

• Gwenna, Eyes of Gaea on the battlefield
• Temur Sabertooth on the battlefield
• Phyrexian Dreadnought in hand
• Training Grounds 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 Phyrexian Dreadnought by paying
3. Gwenna triggers, putting a +1/+1 counter on it and untapping it
4. Phyrexian Dreadnought enters the battlefield, triggering itself
5. Holding priority, activate Temur Sabertooth by paying , returning Phyrexian Dreadnought from the battlefield to your hand
6. Resolve the Phyrexian Dreadnought ability, failing to sacrifice it due to it no longer being on the battlefield
7. Repeat

Results

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