Ran into an unknown during my bi-weekly Dead Suns AP run, my technomancer rolled a crit for caustic conversation. Did the usual crit damage but we were unsure how to handle the remaining damage per round, should that be double as well? Had a couple paizo folks in the group and we all were a bit stumped.
You fling magical nanites that convert water vapor around your target into deadly acid. Make a ranged attack roll against your target’s EAC. If you hit, the target takes 4d4 acid damage and it takes 5 additional acid damage at the end of its turn each round for the spell’s duration.