Basic Strat;
Pull mob.
Burn Mob to 50%
Mount Splits
Tank Mount somewhere
Take mount down to 20% ish HP.
Go back to killing Named
Named ports up out of reach around 10% ish - Will pop red circle on random raid member, must move out of it, or you will die and heal named 5% per death.
Kill Mount
Named rejoins fight
Kill Named

Things to watch out for;
Red Circles when Named is in the air.
Any death heals named 5%. If he goes back above 50% hp, his mount rejoins him.
Has a Knockback AE (Fracture)
Randomly ports the odd person to to him.
Has a Trauma based AE of some sort, doesn't seem to do much.
Free loot.

Thats great info to start

You beat on Jalkhir until he and the mount split. The offtank drags Essedaria down the hall a bit and everyone burns Essedara until she's at 10% or so, then go back to Jalkhir.

Somewhere towards the end of the fight everybody needs to be on the same wall of the hallway because there's some detriment cast on a random raid member that makes a hard-to-see circle on the floor. The raid jousts to the other side of the hallway when this happens.

Avoid deaths, you get enough deaths and Jalkhir gets a spear-and-magic-helmet insta-fry that wipes your raid.

Anybody willing to share information on this encounter?