Pentavus, Cathars' Crusade, and Phyrexian Altar

Prerequisites

• Pentavus on the battlefield
• Cathars' Crusade on the battlefield
• Phyrexian Altar on the battlefield
• Pentavus has at least two +1/+1 counters on it
• available

Steps

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

Results

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