Emeria Shepherd + World Shaper + Altar of Dementia + Trenching Steed

Emeria Shepherd

World Shaper

Altar of Dementia

Trenching Steed

How it works

1. Activate Trenching Steed by sacrificing a land.
2. Repeat step 1 until you control no lands.
3. Activate Altar of Dementia by sacrificing World Shaper.
4. When World Shaper dies, it triggers, return all lands from your graveyard to the battlefield tapped.
5. When the lands enter, Emeria Shepherd triggers that many times.
6. Resolve an Emeria Shepherd trigger that was triggered by a Plains, returning World Shaper from your graveyard to the battlefield.
7. Resolve all remaining Emeria Shepherd triggers.
8. Resolve the Altar of Dementia ability.
9. Repeat

This loop turns the recursive self-sacrifice of Trenching Steed into a self-sustaining engine fueled by World Shaper and Altar of Dementia. By sacrificing your lands to pump Trenching Steed until none remain, you clear the board to feed World Shaper to Altar of Dementia. When World Shaper dies, its trigger floods the battlefield with all those lands, waking up Emeria Shepherd's landfall ability to continuously resurrect World Shaper and any other nonland permanents you desire.