If you're doing this in level 80 gear, on level, with a group, you might want to take note of the location, near Bi'titu that has a climbing wall so you don't take damage and end up immediately in combat with the linked mob of devourers at the bottom. When you see the three sisters spawn, burning them down in alphabetical order works, or you can burn the two from the side down together and handle the one from the center last, either way don't try to kill the lady whose name begins with X until last unless you're really OP for the zone. Druzella casts a bone shield which reflects damage. If you're doing it on level, you will want to be sure to keep all mercs, pets and yourself fully passive while she is cocooned in bones. Joust the AoE,s he is rooted while in that state.
If you're trying to find the fastest path to Druzella for the KA Signature quest, in the agnostic version, Kill Gear and then go directly to the three sisters and then Druzella. Beware that in the agnostic version it's possible to have other people in the zone with you and not be aware of it, agnostic is basically a "contested" zone. Use /who as you go. If someone beats you to Druzella, just zone out and re-enter, it has no lockout or persistence time.