Ignore the fact that I'm a Mistweaver; I was a raiding Disc priest pre-MoP, and I am the hand-holder/spoon-feeder to our current Disc priest who used to be a resto druid. I still raid on my own Disc priest with another guild's alt run, as well.
To those who've joined the conversation since the end of the first page - keep in mind this priest was Holy until incredibly recently. He's going to be absolutely *lost* - spell-usage-wise and, more importantly, conceptually. His gear's not going to be set up properly for Disc (since it wasn't set up properly for Holy either >.>)
There's excellent gear advice above, and critique of what he's doing *wrong*. There's also some good info as to what he should do instead, but I just want to be sure to consolidate it all into one post for easy reference. Remember that our OP, while an incredibly helpful person and excellent team player, doesn't know priests and the info won't just file itself in his/her head 2 items from one post, 3 from another, one from a post farther down the page... and then present iteself in coherent and useful fashion when s/he is talking to the priest.
I'm going to start with the very, very basic minimums because I'm going to assume *ignorance* not laziness on the priest's part; it is indeed possible to be this clueless if you've never been a part of an organized raid before and simply don't realize everything that goes into building a successful team... and that that begins with *you*.
#1 - Ask if s/he has DBM (turned out our resto druid didn't have it until we were working on H Spine in DS. Yeah, it was later on, in the 25% nerf region, so no it wasn't like we're talking 0% H Spine with no DBM... but... yeah).
#2 - Describe to him/her how incredibly powerful Disc is with Spirit Shell, Archangel, and Power Word: Barrier. Initially, don't try to stress any other points to improve on (spell-usage-wise, I mean). Focus on those three, or s/he will become overwhelmed, imo. Considering the type of player the armory & logs point to.
#3 - Explain how Disc doesn't excel at "filling up green health bars" - Disc excells at "making sure the green health bars never drain in the first place". It's less true now than it was in Cata, because of the improvements Blizz made to Archangel (... so... we're not so awful as we used to be at filling up the green health bars)... but that concept is *crucial* to get through a new Disc priest's head, especially if they cut their teeth healing as Holy priest or resto druid. Tell him/her that Spirit Shell is an incredible, OP tool to prevent health bars from draining.
#4 - Explain that most big damage mechanics are timed and predictable. This is where they need to get familiar with DBM. They can go into the DBM interface and filter out all sorts of timers which are not crucial for him/her, so s/he can *focus* on the big important ones s/he should be timing his/her use of Spirit Shell with. I mean, it's not necessary to filter stuff out of DBM, but let's just assume they're going to have difficulty keeping track of multiple timers and unfamiliar cooldowns which are to be used in a completely different way than anything they've ever done while healing before.
#5 - Ideally, the priest will learn when to Holy Fire, when to Smite, and when to use Penance offensively, to stack and maintain Evangelism so that they can use Archangel at a moment's notice, and also, *eventually*, to add extra dps to the fight where possible. At first, all you should stress is that the priest should NEVER have Holy Fire sitting off cooldown. Holy Fire should be glyphed for Disc so that it's instant, so that it's a no-brainer to punch that button every time it comes off cooldown. HF has a 10 sec cooldown; Evangelism stacks have a 20sec duration before they fall off if not refreshed. If your goal is to use HF on cooldown, you will *never* have your Evangelism stacks fall off (thus losing access to Archangel), even if you're a few seconds late on actually using it.
#6 - When is the right time to use Archangel? Often :) I won't say on cooldown, although that's probably better than using it too infrequently... If you really push building Evangelism stacks (ie, adding an offensive Penance and Smites to your HF), you can have it available every 30sec. 18 sec of 25% extra healing, as often as every 30 sec? Yes please, sign me up, and get that priest using HF on cooldown! In reality, you'd spend so much of your current Archangel time "priming" for your next Archangel that it's not usually what we shoot for (using Archangel on cooldown); after all, we've popped Archangel because we want 25% more healing, right? Presumably we have to actually use *heals* while Archangel is active, not spend time Smiting. As a general rule.
(con't cuz I'm long-winded...)
Edited by Meditation on 12/29/2012 3:17 PM PST