Relevant Talents used:

Body and Soul
Mindbender
Desperate Prayer
Divine Insight
Divine Star

iLvl: 523

I was quite excited that this was gonna be my kill attempt that I ended up totally messing up the ending lol.

Cho'gall is a 2 phase fight. Phase 1 lasts until 25%, this is where most of the mechanics take place. Phase 2 is a simple tank and spank phase with the occasional add that needs to be killed.

Corruption:
Throughout the fight, there will be a corruption bar. Corruption increases if the player gets hit by certain abilities. In phase 2, Corruption will slowly increase inevitably. If corruption reaches maximum of 100, players can no longer be healed but they deal double damage. Basically corruption should not be reaching 100 unless boss is nearly dead.

Phase 1:
The main mechanics to watch out for are: Fury of Cho'gall, Summon Adherents, and Fester Blood. Fury of Cho'gall is a stackable debuff cast every 45sec that increases physical damage taken by 20% and lasts 1 minute. Basically the most important debuff to watch out for and should never reach 2 stacks. Rotate Mindbender so that it can eat every second debuff for you, allowing you to drop stacks. Cho'gall will also summon large Adherent adds which hits quite hard. A defensive/healing CD is recommended each time these Adherents spawn. It is also preferable to kill each Adherent in the same spot. Once killed they will drop a pool on the ground. Cho'gall will then cast Fester Blood summons 5 small adds called "Blood of the Old God" from each existing pool. Do not get hit by these small adds as each hit from them adds a large amount of corruption. AoE these adds down ASAP.
The other mechanics in this phase can be ignored.

Phase 2:
Cho'gall no longer summons adds from phase 1 but will continue to cast "Fury of Cho'gall" as well as summoning a new type of add called Darkened Creation. These adds channel a Debilitating Beam onto the player that reduces damage and healing done by 75%. There are a couple of ways to deal with this. The first is to cast Mind Blast followed by instant Devouring Plague before it can start to channel. The second is to use Silence to interrupt the beam channel. Other than that it's basically a race to the finish. Do keep in mind to reset Fury of Cho'gall stacks with Mindbender though. Like I said earlier, I was quite excited that this was gonna be my kill attempt that I ended up totally messing up the ending, didn't even realize I had an add channeling on me till the boss died. Was wondering why he was dropping so slow lol.
(Correct way would have been set Mindbender on boss, Silence the add, throw a 3orb DP on it, then back to boss. That way I wouldn't have come anywhere near as close to a wipe).

Corruption: Acceleration:
This is a debuff that is gained when the player reaches 25 Corruption. This debuff increases corruption over time so it must be dispelled. It is more preferable to get this debuff and dispel it in phase 1 when there is less mana and GCD stress.