Reaper King, Serra Avatar, Atla Palani, Nest Tender, and Maskwood Nexus

Prerequisites

• Reaper King on the battlefield
• Serra Avatar on the battlefield or in the library
• Atla Palani, Nest Tender on the battlefield
• Maskwood Nexus on the battlefield
• You have a way to cause a creature to enter the battlefield under your control

Steps

1. Cause a creature to enter the battlefield under your control by any method
2. When that creature enters the battlefield, Reaper King triggers, destroying that creature
3. Resolve Atla Palani's trigger, revealing cards from the top of your library until you reveal a creature card and putting it onto the battlefield
4. Repeat from step 2 until Serra Avatar enters the battlefield then dies, or until you choose to end the loop by destroying an opponent's permanent
5. If Serra Avatar dies, it and Atla Palani trigger
6. Resolve Serra Avatar's trigger, shuffling it into your library
7. Continue from step 3

Results

• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Put all creatures from your library onto the battlefield, then they die