Xavier Sal, Infested Captain, Agatha's Soul Cauldron, Basking Broodscale, and Barrenton Medic

Prerequisites

• Xavier Sal, Infested Captain on the battlefield
• Agatha's Soul Cauldron on the battlefield
• Basking Broodscale on the battlefield
• Barrenton Medic in exile
• Barrenton Medic exiled by Agatha's Soul Cauldron
• Xavier Sal has at least one +1/+1 counter on it and do not have summoning sickness
• Basking Broodscale has at least one +1/+1 counter on it
• You control at least one additional creature

Steps

1. Activate Xavier Sal's second ability by tapping and sacrificing it, putting a +1/+1 counter on it and Basking Broodscale
2. Basking Broodscale triggers, creating a creature token
3. Activate Xavier Sal using Barrenton Medic's second ability by putting a -1/-1 counter on it, untapping Xavier Sal
4. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite creature tokens
• Infinite proliferate
• Infinite +1/+1 counters on Basking Broodscale