Twin consorts heroic.

[Alarinth]

If your affliction lock has the UVLS trinket, ask him/her if he/she is comfortable with Demonology - if he/she is able to get a Doom with 100% crit up on the target that is disappearing on the pull, he/her will do monstrous dps throughout the entire fight.

[Reubane]

Grats on killing twins. The tips that helped my guild go from struggling to wtf how did we ever wipe to this?

Solo tanking 1st phase with 2nd tank drawing cranes at the start and then taunting suen around the room. Beasts die insanely quick, at least they should.
Saving every 3rd crystal spawn for inferno.
Using cranes start of phase 3 to hit both twins and using other celestials for tidal waves as seen fit.
Eminence and Atonement won't give debuff from beasts of nightmare and hots seem to only proc it on 1st tick.