Hecatomb + Cacophodon + Roaming Throne + Nim Deathmantle

Hecatomb

Cacophodon

Roaming Throne

Nim Deathmantle

How it works

1. Activate Hecatomb by tapping an untapped Swamp you control, dealing 1 damage to Cacophodon.
2. Cacophodon triggers twice, untapping two tapped swamps you control.
3. Activate a Swamp you control by tapping it, adding .
4. Repeat steps 1-3 until Cacophodon has 4 damage marked on it.
5. Activate Hecatomb by tapping an untapped Swamp you control, dealing 1 damage to Cacophodon.
6. Nim Deathmantle triggers and Cacophodon triggers twice.
7. Resolve the Nim Deathmantle trigger, paying 4 to return Cacophodon to the battlefield.
8. Resolve both Cacophodon triggers, untapping two tapped Swamps you control.
9. Repeat from step 1.