Most unavoidable mechanics should never one shot you. If they hit hard, there is likely a raid cooldown used for this.
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.