How you decide to approach Skorpyron will depend on your raid group and where your tanks are tanking the boss. There's generally 2 different approaches for this fight: you either tank Skorpyron where the adds run out so your raid can instantly blow up all of the adds, or your tanks hold Skorypyron inside the outer circle so you encounter as little adds as possible. Generally for LFR/normal/heroic versions of this fight, tanks will tank at the spot where adds funnel out and your raid can go ahead and aoe down the adds. For mythic, most groups just tank the boss closer to the center of the room so the group deals with as little adds as possible.
For talents, there's actually a few options you can pick for this fight depending on whether you want to just pad on aoe or if you want to burst the boss down asap. This is also the only fight in Nighthold where you can actually experiment with not taking Inner Rage. I have provided 3 different talent set-ups that you can go with for this fight. The talent choices get progressively more aoe pad centric as you move from left to right (or top to bottom if you're on your phone).
The "Single Target" build focuses on burning down the boss and you're going to be using all your cooldowns on pull including using Potion of the Old War as your pre-pot. Depending on how fast your raid group breaks his exoskeleton to proc Exoskeletal Vulnerability, the 2nd casts of your Draught of Souls could perfectly line up with this. The 100% damage increase from that debuff does indeed buff your DoS and Potion of the Old War damage (so your 2nd pot should be when the debuff is up). This talent set-up is generally only needed for Mythic versions of the fight.
For the other 2 talent builds, you're going to be focusing more on aoe and killing the adds than the boss. You'll be using Potion of Prolonged Power as the pre-pot and the 2nd pot later on (whenever a new set of adds is about to come out). The Bloodbath build is really strong if you have a Convergence of Fates since you will most likely have Bloodbath and Battle Cry up on every add spawn or every other add spawn. It's also your only chance to use Bloodbath as a talent and it's nice to switch up our play-style once in a while.
Legendaries and Trinkets
For Legendaries, Naj'entus's Vertebrae, is going to be the best performer since it's such a good legendary for aoe whenever there's at least 3 targets. It also synergizes very well with Wrecking Ball. Kil'jaeden's Burning Wish is another great legendary if you're trying to get as much aoe damage for yourself as possible since it's instantaneous aoe damage. Do note that even though KJBW doesn't work with any of our buffs, it does however work with the Unrivaled Strength trait, so you still want to use it during Battle Cry.
As for trinkets, Convergence of Fates is great since it reduces the CD of our Battle Cry and could potentially allow us to have a BC for every add spawn. Draught of Souls of course is always a great trinket if your goal is to burn down the boss. I actually wouldn't recommend Windscar Whetstone on this fight unless your group has little burst aoe and the adds actually survive long enough for the full 6 seconds of the damage from the trinket to go out. Terrorbound Nexus and Claw of the Crystalline Scorpid are good alternatives if you don't have CoF+KJBW combo. The reason why I value KJBW so highly is because it has such a short cooldown and you can choose when to use it. Of course if Terrorbound Nexus procs on every add spawn multiple times, it's great, but you can't be sure of that.
As far as for timers on this fight, you are going to be tracking when small adds are spawning (Call of the Scorpid), when Shockwaves are coming out, and when the boss will proc Exoskeletal Vulnerability. Due to the nature of the boss being stunned when Exoskeletal Vulnerability is procced. The timers all change slightly once this is triggered for the first time.
Call of the Scorpid will generally cast around every 20-25 seconds as long as the boss isn't too busy doing something else or stunned. First cast is 21 seconds into the fight.
Shockwave will generally cast at around 1:05-1:10 into the fight and again at around 2:20-2:25 into the fight.
Exoskeletal Vulnerability will cast once the bar below Skorpyron's hp reaches 100%.