Triskelavus, Cathars' Crusade, and Phyrexian Altar

Prerequisites

• Triskelavus on the battlefield
• Cathars' Crusade on the battlefield
• Phyrexian Altar on the battlefield
• available

Steps

1. Activate Triskelavus by paying and removing a +1/+1 counter from it, creating a 1/1 Triskelavite artifact creature token
2. The Triskelavite enters the battlefield, triggering Cathars' Crusade, putting a +1/+1 counter on each creature you control
3. Activate Phyrexian Altar by sacrificing the Triskelavite, adding
4. Repeat

Results

• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers
• Infinite +1/+1 counters