Emeria Shepherd + Aftermath Analyst + Troubled Healer + Horizon Explorer

Emeria Shepherd

Aftermath Analyst

Troubled Healer

Horizon Explorer

How it works

1. Activate any number of lands by tapping them, adding at least 3.
2. Activate Troubled Healer by sacrificing a land.
3. Repeat step 2 until you control no lands.
4. Activate Aftermath Analyst by paying 3 and sacrificing it, returning all lands from your graveyard to the battlefield untapped due to Horizon Explorer.
5. When the lands enter, Emeria Shepherd triggers that many times.
6. Resolve an Emeria Shepherd trigger that was triggered by a Plains, returning Aftermath Analyst from your graveyard to the battlefield.
7. Resolve all other Emeria Shepherd triggers, returning any number of nonland permanents from your graveyard to either your hand or the battlefield.
8. Repeat.

This loop begins by using Troubled Healer to clear your board of lands, sending them and Aftermath Analyst to the graveyard. You then crack Aftermath Analyst's activation to flood the battlefield with all those lands at once, while Horizon Explorer ensures they enter untapped. Because those lands are hitting the field, Emeria Shepherd triggers for each one, letting you use the Plains triggers to pluck Aftermath Analyst right back out of the graveyard and repeat the cycle endlessly.