Andras the Black Dog
He summons a necrotic troll that one-shots almost any individual party. He also gets initiative.
Other than waiting until I have a level advantage how I can deal with this goon?
There are a few options I could recommend but unless you provide some more information about your party and levels I can't give you every idea.
Get your level high enough, if you are under leveled, most fights are difficult. It is usually easier to level up elsewhere and come back. It is also important to make sure your gear is also up to date. You may be an appropriate level, but if you have under leveled gear you won't stand much chance against higher level enemies.
-
Take your tankiest character and have them initiate the fight, you can either talk to the dog with pet pal or straight up attack him to initiate the fight. While you do this, have every other character in your party be in sneak away from the area, out of sight entirely and broken in chain from the one starting the fight.
2a. You will want to use each other character one at a time, and move them into the fight, attacking the dog from sneak mode for a free move. All the while don't be advancing the fight with the one who initiated it. Your goal here is to take out the dog first. Summons will automatically die if you kill the one who summoned it.
If you have the shackles of pain skill, have the one with that skill initiate the fight with them and cast it onto the dog after his armor is removed. How you go about this is up to you. (You could use the sneak tactic again to remove armor).