Most unavoidable mechanics should never one shot you. If they hit hard, there is likely a raid cooldown used for this.
On mythic, this boss doesn’t change much but the numbers might be tight before getting some mythic gear.
Therefore, it is paramount that you can bring the biggest numbers and ensure burning pitch is not an issue.
Therefore, I recommend being aware of burning pitch timers:
Burning pitch happens around 0:45, 2:15, 3:49 and 5:07.
The adds spawn right around 3 seconds after these casts start.
Here is an example of CD planning for a 5:45-6 minutes fight:
0:00 : Touch of death, SEF
0:40 : you can use a second SEF inside of Prolonged power here; it will cover strike of the windlord and the first add spawn.
2:10 : you can use touch of death here, dealyed by 10 seconds, followed by another storm, earth and fire covering this and the add spawn at 2:18.
3:52 : you can use SEF here again, covering one of the harder add spawns.
4:30 : start being aware of boss HP and when to use your second prolonged power potion.
5:10 : here is a good occasion to use SEF on the hardest add wave, followed by your last touch of death/touch of karma with single target cooldowns on boss to finish it off.
If things go wrong, you can easily soak a Slam on Heroic with a large health pull and Touch of Karma. I would encourage popping Prolonged Power prior to this for extra safety. This only comes in handy if tanks are to die, but remember it is a possibility. If you are specced into Dampen Harm, this plus Touch of Karma makes for a very easy soak on Heroic.