Shepherd of the Cosmos, Phyrexian Altar, and Necrogen Communion

Prerequisites

• Shepherd of the Cosmos on the battlefield
• Phyrexian Altar on the battlefield
• Necrogen Communion on the battlefield
• Necrogen Communion attached to Shepherd of the Cosmos

Steps

1. Activate Phyrexian Altar by sacrificing Shepherd of the Cosmos, adding one mana of any color
2. When Shepherd of the Cosmos dies, Necrogen Communion triggers, returning Shepherd of the Cosmos from your graveyard to the battlefield
3. When Shepherd of the Cosmos enters the battlefield, it triggers, returning Necrogen Communion from your graveyard to the battlefield attached to Shepherd of the Cosmos
4. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite colored mana
• Infinite sacrifice triggers
• Infinite death triggers