Omarthis, Ghostfire Initiate + Helm of the Host + Forsaken Monument

Omarthis, Ghostfire Initiate

Helm of the Host

Forsaken Monument

How it works

1. At the beginning of your combat phase, Helm of the Host triggers, creating a nonlegendary token copy of Omarthis with haste.
2. Put a +1/+1 counter on the Omarthis token or another colorless creature you control.
3. The nontoken Omarthis triggers, putting a +1/+1 counter on itself.
4. The Omarthis token triggers, putting a +1/+1 counter on itself.
5. Repeat from step 3.