Something else to point out on heroic is the number of players you have. Towards the end, my group had 10 people doing the standard 2/2/6 comp. I won’t go into every detail about each person, but we couldn’t pull it off.
I opted to go with a friend for two of my wins and pug two others and I can point out something very apparent: this fight is exponentially easier with more people. More healers means you have more CDs to hit during P2 when the adds are casting their nonsense. They also can delete the healing absorb on p3 because no matter your roster, it is only ever two people who get it.
Similarly with DPS, on p3 two people are jumping around during arrows. With a 10 man group, that’s a third of your DPS dodging mechanics and being away from the boss. Same thing with darkness. It really sucks having one or two melee sitting on their hands. But with 20 or 30 people? Just CD and heal through it, go ahead and spread that darkness.