The quest is working now but I was sure it was broken because of the way it's scripted. The event's a really cool one but overdoes it a bit on dramatic pauses. If you're doing it and nothing much seems to happen, just wait some more.
After you talk to X'iri nothing happens for a bit, then after a while he gives you the buff thing. X'iri's forces run in and fight, and this goes on for quite some time (you'll see reinforcements running up the road from the Aldor and Scryer FPs). Most of the fighting is done by these guys. Vargath and his mates will spawn and stand around being ugly.
Sometime after that - they really do take AGES - Akama and Maiev will show up. I suspect they've /walked all the way from the warden's cage.
It's easiest just to hang with X'iri and wait, then when you see Akama and co. wandering up from the main road, stick with them. Akama engages in some fighting but not a lot. Just watch the dialogue and emotes and follow him to the crack in the wall. The quest completes as he goes inside. You don't need to go with him, just go back to X'iri to hand in and get your Medallion of Karabor.