Spawns lvl 70 ^^^ adds that autoattack for cold damage and are immune to cold damage.
Alzid also casts fear probably every minute or so.
Adds spawn throughout the fight, and will split into two if you don't kill them fast enough.
Have the secondary tank grab the adds when they spawn, and immediately concentrate all firepower on the adds, then go back to the name. Make sure to pull the adds far enough back so the raid is out of the point blank AE's of Alzid.
Rinse and repeat to win.
One thing that help speed up the fight, are to use all summoned pets, including dumbfires, on the Uncaged Alzid. This will help continually burn him down while allowing your force to switch to the spawned blobs.