A few things to note that were omitted due to the short duration of the fight.
Heroism/Bloodlust is best used when Keleseth is empowered. This is because on both of the other bosses you are constantly moving out of his special ability (either vortex or flame orb). Threat may be an issue if Keleseth is the second empower so make sure to feed as many misdirects and tricks into the warlock tank as possible.
For reference, we were calling the front of the room where the bosses start and the back of the room the area by the door.
We used 5 healers, 2 resto druids and a holy priest for raid healing and a paladin with beacon and a disc priest healing the 3 tanks. Aside from empowered Keleseth the warlock tank does not need much healing as long as he or she is good with the orbs. You can see my damage taken through the video and I can honestly say I am not sure how much damage the Taldaram tank takes.
When I saidIt was originallyKeleseth never meleesbut was lost in editing.As long as you do not run into melee range of him, Keleseth never melees
-Rewind the video to 3 minutes 1 second to see the event I am referencing.When valanar gets emopowered the second time, he almost immediatly started casting empowered vortex. Make sure your melee are away as we wiped on a previous attempt to several melee getting blown up at the exact same point as in this video. The reason for that is that the old empower does not stop casting when the invocation switches, and we had both an empowered flame orb and an empowered shock vortex go out at the same time.
Finally, I apologize for the amount of info that needs to be added in text due to the short nature of the encounter.