Firstly, is there a way I can rescue Halsin and save the grove without aggroing the entire goblin hideout? Specifically Razglin, it seems like there's no way to kill him that doesn't get the whole camp hostile, but maybe that's been fixed in the latest patch?
Unless things have changed in the last patches, how I have done this area should still be valid.
You should be able to disguise yourself as or play as a drow and get into the hideout without issue. You don't have to fight any of the goblins outside if you use fast travel and don't plan on coming back to the area. If you really want to, then you can poison the cauldron to help weaken them (think you have to pass a speech check if they catch you) but don't bother with them anymore until you are done with the inside. Once inside, start killing from the back and work your way out.
The room with Minthara can be taken care of without alerting the rest of the place, usually my party stays on top of the walls and snipes everyone with use of crowd control spells to keep everyone in the room. I feel like there was a chest or barrel up there that helped block enemy hits, but this may have changed.
Priestess Gut can be taken care of in a similar manner. If you pretend to go along with her suggestion to get her into the side room, there is a way to also get your party on the rafters if you want here as well. Silence is useful here, also use Chill Touch cantrip to prevent healing. Clearing this area will bring in some of the adds and also the vendor unfortunately, set area spells by the doorways so they have to walk through them to get to you.
I would recommend doing these first two parts before rescuing Halsin because he doesn't understand the concept of stealth and infiltration.
The last section you should have to fight is Razglin's area. Again, rafters are great, just don't clump up your party (never do this anyway) because some of the goblins here like to use acid. There are two chandeliers that can be shot down in this room, try to have something flammable under them like Web or Grease for more effect.
There are ladders in some of the areas that you can destroy to make it harder for enemies to get to you. If you find that they start swarming the main ladder that can't be destroyed, then throw down Grease or something to get them in a clump then use AoE spells to take them out.
All my suggestions are from someone who hates melee combat so please take this into consideration. I am sure there is some sort of shove cheese that can be done with the pit, but never tried it myself.
