I use my LB in dungeons when I know its safe to do so. It can remove 10% off a boss' health in expert, which is a nice chunk, though it's used mostly as a finishing move.

I just wish SE would rework the LBs. I loved Skillchains in FFXI and I would love to see something like that come back, where there are individual LBs that people can chain together for greater effect.

Though it probably would see backlash from the less skilled players or random groups who have trouble chaining properly.