Before Pull
Pop a shadow prot pot.
Assign the shackle thingy and chose a raid mark for your shackle target.
Make sure to have magic dust and/or goblin rocket helmet to CC lost adds.
The shackle thingy
So there are two “sides” on this boss, one for melees and one for casters.
On the caster side (that’s the only one you’re interested in as priest), there are wave of mobs spawning from 3 spot. I’ll call those spot “left, middle, right”. There are 3 kinds of mobs spawning : trainees, DK, horseguy. The guys we are shackling are the DKs and only spawn from left or right side.
Usually, the first two waves of DK are killed and the waves 3-4-5 are shackled.
You’ll get an assign such as “Holyprane – 4th DK right” for example. Check your side (left or right), and go more or less in range of where the DK will spawn to be able to shackle it as soon as he spawns.
The shackles need to be refreshed throughout the fight, so to keep in track the assignment of everyone, you’ll have to put a raid mark on yours.
To make things simple, you can use this macro that will shackle and mark the target at the same time:
You just have to change the number to match the mark you want.
The fight
The most important thing is to keep your assign shackle.
Concerning the healing, it can get intense depending on how the adds are managed. You can take agro on trainees that will hurt and pushback casting, so remember to spam fade on CD.
During chill phase, spread renews preemptively. And when there is a lot of hp deficit on the raid, top everyone with ph/heal/gh
If you have adds on you, don’t forget to use fear / magic dust / goblin rocket helmet