Pentavus, Cathars' Crusade, and Urza, Lord High Artificer

Prerequisites

• Pentavus on the battlefield
• Cathars' Crusade on the battlefield
• Urza, Lord High Artificer on the battlefield
• 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. When the Pentavite enters, Cathars' Crusade triggers, putting a +1/+1 counter on each creature you control
3. Activate Urza's first ability by tapping the Pentavite, adding
4. Repeat

Results

• Infinite +1/+1 counters on creatures you control
• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite sacrifice triggers