Pure ranges DPS snore fight, shazzrah's an easy one to beat after garr/geddon.

Abilities

Deaden Magic: Reduces the magic dealt to shazzrah down to almost nothing. Purge/dispell this.

Blink: Shazzrah will blink into a random raid group every 45 or so seconds. Whoever he targets needs to run towards the MT.

Arcane Explosion: Deals thousands of damage in a large area of effect.

Shazzrah's Curse: Increases magic damage dealt to players, can be dispelled.

AoE Counterspell: Silences a group of people

Pull

Seperate your raid into 8 seperate groups stationed in a circle around Garr's room. Pull shazzrah into the center where your MT will be waiting, your melee classes have to sit this one out.

Fight

Shazzrah will cast his magic damage reducer quite a bit so be ready to get rid of it lest you waste alot of damage. If shazzrah blinks and isn't run back to the MT quickly he can destroy parts of your raid with his AoE.

Your MT should have no problem by now with tanking Shazzrah, he dosen't really do much damage and only his blink should mess you up at all.

If your raid is prepared to deal with the silences/blinks this is a breeze.