Dunno, I didn't figure out a gimmick when the game pitted me against her in the ship, I just wailed away at her before she could finish ruining the wax voodoo doll. Since she attacks it and not you, if you have the damage output it's a ludicrously easy fight.
I got a panther pet from one of the boss fights (out of about six plus kills) so they don't drop a lot. Haven't yet been able to confirm whether they are just boss fight drops or any green box, since the pets are green items.
So far I've seen a panther and a large rat.
I tried to do it with my BS: could get the rats down and then he didn't hit very hard but then he just recasts the rats and I can't keep up with them. I don't know if an aoe caster could get the rats down with him fast enough to do the pirate boat rat boss version or not.
It is frustrating though. It would be nice to know if this is really bugged and up for fixing or not. I'm on cooldown now hoping for one of the other versions which I can do pretty easily with demo or bear.
I could be wrong, but it seems like kicking the barrels provides some protection to the doll, so I kick at the very start, and then every 30 seconds or so.
The main thing seems to be to dps Vayaspara. Since she stays focused on the doll, you can get behind her where she has no shields and get regular crits. As she pops adds, do some kind of AE and pull them to her and dps all three.
Drostan I have no idea. Aside from standing on barrels where the rats can't reach, I haven't found anything that works. And melee from the top of barrels seems impossible.