Thran Vigil, Carrion Feeder, and Gravelgill Axeshark

Prerequisites

• Thran Vigil on the battlefield
• Carrion Feeder on the battlefield
• Gravelgill Axeshark on the battlefield

Steps

1. Activate Carrion Feeder by sacrificing Gravelgill Axeshark
2. When Gravelgill Axeshark dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
3. Thran Vigil triggers, putting a +1/+1 counter on Gravelgill Axeshark
4. Resolve the Carrion Feeder ability
5. Repeat

Results

• Infinite +1/+1 counters on a creature
• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite sacrifice triggers