Collin throws another rock, thinking to himself, This seems to be variously effective against things. Might want to work on that.

ac 6 - (d20)[10]
physical rock - (d10+7)[15]

Coa doesn't see any reason to not continue what's been pretty effective so far.
ac 2, flinch on 15-20 - (d20)[15]
physical dark - (2d10+22)[26]