Emeria Shepherd, Wormfang Newt, and Phyrexian Altar

Prerequisites

• Emeria Shepherd on the battlefield
• Wormfang Newt on the battlefield
• Phyrexian Altar on the battlefield
• You have a Plains exiled by Wormfang Newt

Steps

1. Activate Phyrexian Altar by sacrificing Wormfang Newt, adding one mana of any color
2. When Wormfang Newt dies, its second ability triggers, returning a Plains from exile to the battlefield
3. When the Plains enters the battlefield, Emeria Shepherd triggers
4. Holding priority, activate the Plains by tapping it, adding
5. Resolve the Emeria Shepherd trigger, returning Wormfang Newt from your graveyard to the battlefield
6. When Wormfang Newt enters the battlefield, its first ability triggers, exiling a Plains
7. Repeat

Results

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