Disc priest main:

Your priest should shield the tank (on cooldown), prayer of mending the tank (on cooldown), and other than that be doing atonement dps (penance, holy fire, smite) and take the mindbender talent and use it on cooldown (more dps). Atonement is much stronger than renew so that is a waste of a GCD. Disc priests do not renew*! And you should never ever be going oom while farming stuff, because atonement should be most of your filler healing and it is mostly mana neutral.

Both flash heal and cascade are mana whores and you don't need to be using them in a rotation.

Let me repeat do NOT use renew or flash heal, unless you are driving from the priest and you want to manually flash heal. Spend your time doing passive healing instead.

If your healer is pulling aggro so much that you need a "oh shit don't die healer" macro, I'd a) get better at tanking with the warrior and b) drive from the healer and manually use fade (aggro drop) Healing yourself shouldn't really be this big of an issue. A self shield should be all you ever need

As you aren't going to be flash healing as part of your single target rotation anymore, you also want to take inner focus out. Inner focus should be used either manually to stack a big shield on the tank with a greater heal, or only as part of your aoe healing.

Glyphs for farming should be: holy fire, weakened soul, and either pws or smite, depending on if you'd rather have a little more damage or a little more healing



* The only time I use renew is if I'm having to heal myself on the move and I can't shield myself because of weakened soul