Requires

Omarthis, Ghostfire Initiate must be in hand, or in the command zone. Echoes of Eternity must be on the battlefield. Mirror Box must be on the battlefield. Mana needed: plus enough mana to pay for commander tax, if applicable

Steps

1. Cast Omarthis either from your hand or from the command zone by paying plus commander tax, if applicable.
2. Echoes of Eternity triggers, copying the Omarthis spell.
3. Resolve the copy of the Omarthis spell, creating a token copy of Omarthis with one +1/+1 counter on it.
4. Resolve the original Omarthis spell, causing it to enter the battlefield with one +1/+1 counter on it.
5. The token Omarthis's first ability triggers twice.
6. Resolve the first trigger, putting a +1/+1 counter on the token Omarthis.
7. The nontoken Omarthis's first ability triggers twice.
8. Resolve the first trigger, putting a +1/+1 counter on the nontoken Omarthis.
9. Repeat from step 5.

Results