This is tangential to this thread, but I discovered you can assassinate Halsin in Act 3 camp without repercussions.

I had Astarion the assassin mark Halsin with mark of piercing vulnerability before using the umbral shortsword's power to strike and remain concealed. Halsin was killed out of hand, 150xp, Gale grew temporarily hostile but calmed down after not finding the attacker.

Speak with dead is a bit broken, Halsin's corpse talked about a female Drow killer and unsolved mysteries at Moonrise towers??

Journal said we still had Halsin as an ally for the finale, maybe that'd update,? Or Halsin would resurrect. Who knows?

Packed Halsin in a barrel. Threw water to clean up...

And then reloaded. All a bit silly really. Still, nice to know there's a de-Helsinize camp option.