This fight I hate, nothing really seems to shine on the fight. Even Spirit Shell is quite weak because people have a tendency to be spread too far apart. That said, the best time to use it is just before the Automated Shredder uses Overload.
I use Void Tendrils exclusively when raiding because Psyfiend and Dominate Mind are totally useless and this fight is one of the rare times the level 15 talents are useful because you can root the mines.
Paragons of the Klaxxi
This fight is pretty unremarkable in terms of talents and glyphs as it presents my raid team with very little challenge.
Because of the number of adds being killed I run with Twist of Fate it really pays off on the last phase of the fight as when you need the bigger heals and extra DPS you’re golden. Because of the neat stack of ranged, my level 90 talent of choice is Divine Star because of the positioning we use I get high damage and high healing output from it.
During the 1st phase damage is light. and the DPS is better used killing Garrosh and the adds, wasting a DPS on the Siege Engineer hurts the raid so I am responsible for killing him.
I can keep the tanks in range for healing while waiting for him to spawn and can shield myself when the opposing Iron Star hits the wall. As I stack crit, if I’m lucky Penance and Holy Fire will kill it and a Smite covers the time when I’m unlucky.
During the intermission phases use Atonement as the damage is negligable until Garrosh and keep Prayer of Mending up, PW: Shield up and use Divine Star on CD. If you'[re lucky he won’t cast Annihlate on you and you can stop and cast heals, Prayer of Healing is best.
In phase 2, I group up with the rest of the ranged and continue to use Atonement and focus on the desecrated weapon or the main kill target if the weapon is down. When mind controls come in help DPS them down, if your raid is lacking interrupts use fear to interrupt if you glyph it. During the Whirling Corruptions, Spirit Shell on both mêlée and ranged groups if he gets empowered Whirling Corruption pick up your add and kill it.
When he enters phase 3 it is really show time. It shouldn’t need saying but don’t neglect Prayer of Mending and PW: Shield everyone you can, you should have the mana to do this but the phase shouldn’t last long if you don’t.