Shilgengar, Sire of Famine, Rendclaw Trow, and Hardened Academic

Prerequisites

• Shilgengar, Sire of Famine on the battlefield
• Rendclaw Trow on the battlefield
• Hardened Academic on the battlefield

Steps

1. Activate Shilgengar by sacrificing Rendclaw Trow
2. When Rendclaw Trow 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 Rendclaw Trow
4. Resolve the Shilgengar ability
5. Repeat

Results

• Infinite Blood tokens
• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite sacrifice triggers