Phyrexian Altar, Sneak Attack, Malakir Blood-Priest, and Garna, the Bloodflame

Prerequisites

• Phyrexian Altar on the battlefield
• Sneak Attack on the battlefield
• Malakir Blood-Priest on the battlefield
• Garna, the Bloodflame in hand or in the command zone

Steps

1. Cast Garna; hold priority with her ETB trigger on the stack
2. Sacrifice Garna and Valakir Blood-Priest to Phyrexian Altar, producing
3. Resolve Garna's ETB trigger, recurring Garna and Blood-Priest to hand
4. Activate Sneak Attack to put Garna into play
5. With her ability on the stack, activate Sneak Attack again to cheat out Blood-Priest
6. Resolve Blood-Priest's ETB, draining your opponent' life for at least 2
7. Sacrifice both to Phyrexian Altar in response to Garna's ETB trigger, again producing
8. Resolve Garna's ETB and return both to hand
9. Repeat the loop from step 4 until opponent are at 0 life

Results

• Infinite ETBs
• Infinite lifeloss to opponents
• Infinite LTBs
• Infinite sacrifice triggers