Reaping Willow, Phyrexian Altar, Training Grounds, and Defiant Greatmaw

Prerequisites

• Reaping Willow on the battlefield
• Phyrexian Altar on the battlefield
• Training Grounds on the battlefield
• Defiant Greatmaw in the graveyard
• available

Steps

1. Activate Reaping Willow by paying due to Training Grounds and removing two counters from it, returning Defiant Greatmaw from your graveyard to the battlefield
2. When Defiant Greatmaw enters, it triggers, putting two -1/-1 counters on Reaping Willow
3. Activate Phyrexian Altar by sacrificing Defiant Greatmaw, adding
4. Repeat

Results

• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite sacrifice triggers