Halo Fountain, Phyrexian Altar, and Karn, Silver Golem

Prerequisites

• Halo Fountain on the battlefield
• Phyrexian Altar on the battlefield
• Karn, Silver Golem on the battlefield
• undefined available

Steps

1. Activate Karn by paying , causing Halo Fountain to become an artifact creature until end of turn
2. Activate Halo Fountain's first ability by paying , tapping it and untapping it, creating a 1/1 Citizen creature token
3. Activate Phyrexian Altar by sacrificing the Citizen, adding
4. Repeat from step 2

Results

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