Carrion Feeder, Glen Elendra Archmage, and Hardened Academic

Prerequisites

• Carrion Feeder on the battlefield
• Glen Elendra Archmage on the battlefield
• Hardened Academic on the battlefield

Steps

1. Activate Carrion Feeder by sacrificing Glen Elendra Archmage
2. When Glen Elendra Archmage dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
3. Hardened Academic triggers, putting a +1/+1 counter on Glen Elendra Archmage
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