Gravitic Punch + Kalamax, the Stormsire + Increasing Vengeance

Gravitic Punch

Kalamax, the Stormsire

Increasing Vengeance

How it works

1. Cast Gravitic Punch by paying its mana cost, targeting Kalamax.
2. Holding priority, cast Increasing Vengeance by paying its mana cost or its flashback cost, targeting Gravitic Punch.
3. Kalamax's first and second abilities trigger.
4. Resolve the first ability, creating a copy of Increasing Vengeance targeting the original Increasing Vengeance.
5. Resolve the second ability, putting a +1/+1 counter on Kalamax.
6. Resolve the Increasing Vengeance copy, creating a copy of Increasing Vengeance, targeting the original Increasing Vengeance.
7. Kalamax's second ability triggers, putting a +1/+1 counter on itself.
8. Repeat from step 6 any number of times.
9. Once you have an arbitrarily large Kalamax, have the final Increasing Vengeance copy target Gravitic Punch. This'll create two copies of Gravitic Punch in addition to the original Gravitic Punch.
10. Resolve all Gravitic Punches, dealing infinite damage to each of up to three opponents.