Hunter goes down into the pool and takes his pet to the far side of the pool and then tells him to stay (on passive)(or I guess you could make him aggressive..)(anything that isn’t defensive). Then goes back to join party.
Hunter misdirects onto his pet and then shoots the boss naga lady three times.
She slithers off, down the ramp, around the corner, across the pool and kills the pet (poor pet.. sporeling snacks make them feel better).
In the meantime the party kills off the two water elementals.
With good DPS the elementals can be killed before she gets back.