Frost Mage (Raest Magespear)
Bear Tartare: This gives you a speed boost after killing an enemy. You will be killing lots of the shadowy vestiges with your aoe so you'll be getting tons of boosts. This will help you to get to soaking the runes, to get in cast range of hand of beyond, and to kite the adds. If you're not having trouble with these things, you can sub in your dps food.
Flask: any dps helps
Raid frames: Being able to select your targets quickly is very important as everything is going to be clumped up. Get an addon which will give you target frames that you can click on.
Weakaura (optional): Having a weakaura that shows how much longer your blizzard is up is very useful since you want to be casting two blizzards while your frozen orbs are active. Tracking the cooldown of your orbs is very useful as well because you want to be casting them whenever it's up. There are lots of adds to aoe here, so if you're blizzarding often, you'll get tons of orbs.
Macros: I used a /cast Blizzard macro so I could cast my blizzard's quickly and on the fly.
Talents: I took lonely winter over bone chilling for the single target dps – the water elemental freeze didn't really help much. Shimmer for the double blink while casting – lets you cast your slows while dodging Karam. Incanter's flow for the damage – mirror images died too quick. Splitting ice for the damage – you're generating so many FoF procs with orb spam that frozen touch doesn't really help much and the ice nova ensnare wasn't good enough to justify the damage loss. Frigid winds for the 15% slow. Arctic gale for the blizzard aoe increase – you want to hit as much as possible with blizzard for the slow and orb cd reduction and the unstable magic isn't enough damage (especially since you'll have tons of FoF procs). Thermal void for the single target – comet storm aoe is irrelevant and the glacial spike cast time is terrible for this.
Legendaries: Single target damage > survival > aoe damage. Aoe damage is bad because you want adds up to blizzard and reduce orb cooldown.
Artifact: Highly recommend being 41 with freezing rain skilled. This lets you instant cast 2 blizzards while orb is active. You'll be using orb a lot to generate FoF procs for single target damage, and blizzard to slow adds and reduce the cooldown on orb. It is possible to do it without freezing rain, but if you're that good, you don't need this guide 😉
The main strategy revolves around the blizzard and frozen orb interaction with the freezing rain talent. You kite the adds in the middle, cast orb on them, cast blizzard, dump FoF procs into the priority target, blizzard again, cast orb, blizzard, etc. Keep moving around the circle so the adds stay in the middle. The point is to keep them slowed with blizzard the whole time while spamming orbs for procs for single target damage.
It's important to keep Karam slowed at all times because he will basically 1 shot you he gets into melee range. He also has a stacking buff which increases his movement speed so it gets harder and harder to keep him at bay – however, this resets each time he gets healed. Overall, the fight is based around the concept of kiting while dpsing.
Karam will heal 2 times, so I'm going to break it down based on each life.
After a long RP, Karam will turn into an enemy and attack you. I prepotted here and layed down a preemptive blizzard for the slow. Then orb and icy veins to damage him as much as possible. I blinked over him and my orb so he would keep getting damaged by it and then used another instant blizzard for the slow. The rest is kiting with slows and ensnares. Cone of cold is really strong here because of the 85% slow, but it has a small range so don't get hit! Frost nova him and then run away to keep your distance – don't damage him so your ensnare doesn't break. You might find it helpful to kite him to a flat area so your blink doesn't get caught on stuff.
Once he starts healing, you can damage Raest. Damaging her here isn't too important; do what you can but don't use any cds. She'll start summoning a bunch of adds so start blizzarding them and kiting so the bunch up.
Once Karam heals, he'll start chasing you around again. Kite him into the middle so he groups up with all the other adds. Use the orb and blizzard combo as much as you can to keep them all slowed. Keep moving around the circle so that all the adds stay in the center. Soon after he heals, hands from beyond will start spawning. Save at least 2 FoF procs for these so you'll have the damage to burst them down. When they spawned, I would use my raid frames to select it, then start casting my FoF procs on it. Seeing which direction my ice lances moved let me know where the hand was without having to look around. Knowing where it is lets you adjust your kiting strategy so you don't range it. You'll only be able to interrupt it once because it casts faster than your cooldown, so bursting it is priority. If you're slow, you can use ice block to block it once. It won't kill you, but it'll do about 2/3 your hp. Between hands, dump your FoF procs from your blizzard/orb combo into Karam until he heals again.
This is pretty much the same as his last life, but runes will periodically spawn on the ground. You have to stand in them for a couple seconds or a big add with 100 mil hp will spawn (he speeds up and will 1 shot you just like Karam). If he spawns, it's pretty much game over. You want to continue with the blizzard/orb strategy to kite and dps Karam and the adds while watching where the rune spawns. This is where the raid frames are really helpful as you can watch for the runes and target the hands/Karam as needed. Once a rune spawns, you have a few seconds before you have to soak. Kite the adds away and then blink onto the rune and soak it. A blue cloud will appear to let you know when you can leave. Use hero, second pot, and icey veins here and keep kiting and dpsing until you've killed Karam. Once you've done that, it's easy mode. Just dps Raest until she's dead. Hands will no longer spawn, but you still have to soak runes. She doesn't do much damage; just use frost armor. Then you're done! Click the portal to leave
Hope this helped!