Harbingers Spire Event

[bham]

I took a group into Harbingers last night and we worked our way up the spiral staircase. We stopped at a likely looking place and cleared 3 rooms a few times. 2 named popped but the loot was no better than down below (all 40-50 hp/mana stuff).

We got to the top of the spire and saw the 8 Dragorn Proselytes (sp?). As we were getting ready to pull them the rogue set one foot into the cauldron and 4 or 5 aggro'd immediately, despite us being beyond normal aggro range. I started to evac but we were getting it under control so we killed them off. As they were almost dead, a second wave of mobs, this time Girplans, attacked us. We took these down as well, but a third wave had the chanter out of mana for mezzing and we had to evac this time.

I assume this is some kind of event, does anyone know how much there is to it and what the reward is? We got to what seemed to be the third wave with a group of 66 non-raiders. Any idea what you need to finish it?