Halo Fountain, Aphetto Alchemist, and Phyrexian Altar

Prerequisites

• Halo Fountain on the battlefield
• Aphetto Alchemist on the battlefield
• Phyrexian Altar on the battlefield
• Aphetto Alchemist does not have summoning sickness
• available

Steps

1. Activate Aphetto Alchemist by tapping it, targeting Halo Fountain
2. Holding priority, activate Halo Fountain's first ability by paying , tapping it and untapping Aphetto Alchemist, creating a 1/1 Citizen creature token
3. Resolve the Aphetto Alchemist ability, untapping Halo Fountain
4. Activate Phyrexian Altar by sacrificing the Citizen token, adding
5. Repeat

Results

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