I never realized that she would go in there for any reason other than your prompting the gobbos to bang their wardrums?
It's not about the war drums - I always wreck them first so that I don't get everyone piling on when I pick them off a piece at a time.
I will say that other than potentially losing out on the high dollar gold chest that is tucked away in there, having your mage hurl a fire bolt into the room causes one of the best explosions in the game and usually takes all three of them out immediately or at least knocks down the life of any survivor so that any attack will then polish them off!
Yep, the biggest already-set-up bang in the game. Fun to see, but wasteful of useful materials.
I usually sneak in there and steal the gold almost as soon as I enter the Shattered Sanctum in order to avoid missing out on the bounty and then at whatever point suits me, blow that room to kingdom come. Satisfaction!
Ok, so it probably isn't stealing the gold that triggers her retreat. Good to know.
The trick is to get to the treasure room before you engage in any combat with the goblins (with the exception of Gut, because she's so deep into her lair that the other goblins don't notice if anything happens to her).
I generally pick off the goblins from the edges first and work inward. Sometime during that process, Roah retreats.
