Baradin Hold, Cataclysm's Archavon Vaults, is a mini-raid with 3 bosses inside.
Argaloth was the first one and drops T11 tokens and S9 set. He is a joke, just nuke him. Iceblock his Consuming Darkness (in the video it was removed by Alter TIme), that's basically the only thing that can kill you.
Occu'thar, second boss, drops T12 tokens and S10 set. Second joke. No damage at all, just zerg him.
Alizabal, third and last boss, drops T13 tokens and S11 set. No joke. No joke at all. She is the "Mistress of Hate", and oh, does she deserve that title. This is one of the most infuriating bosses I ever encountered. Alizabal is just random.
Her two core abilities, Seething Hate and Skewer, are on the SAME cooldown and can be cast RANDOMLY.
Seething Hate will put a DoT on you, dealing 600k damage in three pulses.
Skewer will deep stun you for 6 seconds, during which you take 150% increased damage from all sources. You can't Iceblock if you have the debuff, but if you IB before, you will only take 20k (the debuff damage), but will be immune to Ali's hits for the whole duration of the debuff.
The beginning is pretty simple. Assuming your PBoI procs on time, use Alter Time to get rid of the first Seething Hate. Then Iceblock, wait for Skewer to run out. Then dodge her Blade Dance.
The fun begins here. After her first Blade Dance, she can cast either Seething Hate OR Skewer. Randomly.
Just use your Mirror Images a second before the "special". You need a Skewer, so the MI will tank the boss while you're stunned. Then you'll get a Seething Hate, use Cold Snap and a health potion to heal it. Second Skewer, IB it. Second transition, then finish her.