3.08 is launching today, and the hands-down biggest change that will affect priests is the COH nerf.
I apologize for covering this over and over, however it is important to prepare. There WILL be fights that we will need to adjust, but lets see if we can address some of those.
1. Malygos – Vortex. You should be able to get 2 COHs out before the Vortex is over. Also you should be able to burn through charges of ProM. (and a couple of Surge of Light procs will be handy). Generally, if you have been farming Naxx25 you shouldn’t be in too rough of shape as your HP should be well over 20k. You take 20k damage (2k a sec, for 10 seconds) then 10% HP falling damage. Preemptively casting some Shields, renews, and ProM should help temper the learning curve.
2. Loetheb – if you have enough priests in your raid, be sure to spread them out in groups to maximize Prayer of Healing. Watch the debuff timer on DBM, and time your ProH cast to hit after it wears off. Then you can sneak in an instant COH afterwards. If you time it just right you might also be able to get a Holy Nova off too.
3. Thaddius – His chain ligtning is a bear. However it is very important that you keep everyone alive on this fight so you all benefit from the stacking polarity buffs. Mainly flash heal, ProM, and Shaman Chain Heal will thrive here for raid healing.
4. Four Horsemen – With the meteor strike on a longer than 6 seconds cooldown, you should be able to use COH 1-2 times before each Meteor Strike, coupled with a Prayer of Healing and a Flash or two, you’ll be fine. Afterall, if a pally can heal the front half, so can you.
5. Sapphrion – this could be a little trickier. Contant raid wide damage, with a moving blizzard. First and formost, keep Prayer of Mending bouncing! Get a ProM tracker that will help you find out how many charges you have left. With a T7 bonus, this is a very powerful spell on this fight. You also used to be able to heal through hiding behind a Iceblock if a blizzard came by– that could be very tough now.
6. Kel’thuzad – Frost Blast. COH’s instant heal often saved the day on a poorly spread out player, hitting both Frost Blast targets. If your melee can’t spread out and consistantly chain Frost Blast to eachother, entombing all yoru melee DPS. They are gonna die. I can’t tell you how many times our melee failed and chained it to eachother, and if they prevent us from getting The Immortal, I’ll kill them. 
There are other situations where spamming COH has saved the day (pulling too many Gargoyles too soon), however we’ll survive this learning curve. We always have.
Yes, losing the spamability of COH is a nerf, however breaking out other spells will do the job too. A glyphed Flash Heal, Prayer of Mending, Renew, and even Holy Nova all now have a bigger role in our aresenal of spells.
This week will be the one to test it out!
