Shogg will conjure another 20 arrows--made entirely of achemical silver, shaft and all--and casually toss them forward, again just past the monsters if he can...but he puts little effort into it. Rather, he'll attempt to shoot down the other two Rust MOnsters he's already hit.
Spoiler: Actions!
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Free: Conjure Arrows
Move: Toss Alchemical Silver arrows

(1d20+11)[13] (1d10+6)[11]
(1d20+11)[16] (1d10+6)[15]