Talents
First targets for re-allocation would be Body and Soul, Surge of Light, Darkness, and Lightwell, but I don't recommend it.
Lightwell is still underutilized by raid members but it heals pretty well. I find that Desperate Prayer is more distraction than help - I already have plenty of choices for healing myself. I tend to use Binding Heal when I'm in trouble.
Spirit of Redemption is only useful after you've already failed. It can save a close fight but I prefer to focus on keeping everyone alive.
Glyphs
Your primary glyphs will be Prayer of Healing, Renew, and either Lightwell or Flash Heal. Lightwell will be useful for raid healing and tank healing, while Flash Heal will only really be useful for tank healing.
Your major glyphs will be Circle of Healing, Prayer of Mending, and probably Dispel Magic. Fear Ward and Fade can be situationally useful.
Your minor glyphs will be Shadowfiend, Fortitude, and Levitate. The others are mostly useless.
Gear
Intellect > Spirit > Haste (to 12.5%) > Mastery ~> Haste (after 12.5%) > Crit
Reforging/Gems
Intellect is your most valuable statistic followed by Spirit, then Haste and/or Mastery, then Crit.
Haste has value breakpoints that are important to consider. You get one extra tick on Renew at 12.5% Haste. If you can get to 27.2% haste, the 5% raid buff and a Dark Intent can get you one more tick on Renew. After each cap, Mastery becomes slightly better.
- Red Slot: int
- Yellow Slot: int/mas or int/has
- Blue Slot: int/spi
- Meta: Ember Shadowspirit Diamond
Tank Healing
Holy priests have a Chakra for tank healing and a Chakra for raid healing. Serenity is for tank healing. Your Renew will refresh itself automatically in this Chakra, making it easy to keep going. Do make sure you cast it again whenever it falls off. Always use Inner Fire when tank healing.
Your highest heal-per-second sequence on a tank is Holy Word: Serenity -> Flash Heal -> Flash Heal -> Greater Heal. With Serendipity and 12.5% haste you can fit the whole sequence into 6 seconds for an average of 21k HPS and 7.1 HPM (heal-per-mana).
Your highest heal-per-mana is to spam Heal. Generally this is efficient enough that you can do it even when the tank is topped off. This is about 6k HPS and 7.6 HPM, but assuming that you're overhealing it's only 805 mana per second, versus 3000 mana per second for the Serenity sequence.
Generally while tank healing you will spam Heal to keep Renew rolling and have a constant healing stream on the tank. When he takes any significant amount of damage, you hit him with the Serenity/Flash/Flash/GHeal sequence.
Of course you want to change things up according to the circumstance. If you're taking damage too, substitute Binding Heal for Flash Heal. If the tank is topped off after a Flash Heal, just go back to Heal and save your Serendipity buff for later. If you already have a Serendipity buff, just cast GHeal when the tank takes damage. You can always start a Serenity chain if one GHeal isn't enough.
When you're not in a Serenity sequence, be sure to throw out Prayer of Mending if it's cooled down. This will never be overheal on a tank, and it contributes to raid healing too.
Note that much 5man content essentially boils down to tank healing, so Serenity chakra is a good choice for those.
Raid Healing
Sanctuary is your raid heal chakra, I usually trigger it with a PoM. Inner Will can be viable during raid healing but I find that I rarely blow through all my mana in this mode so I generally stick with Inner Fire.
PoM is easy to keep rolling, just hit a tank with it every time you think about it and let it bounce. It's a good death-prevention tool when you're on the move, too, since it's instant.
As a smart heal Circle is one of your best tools. Try to hit someone in a central location so that it has the maximum decision-making capacity. Tanks and melee are usually prime targets. You can also position yourself in a central location and self-target to great effect.
Prayer of Healing is great HPS and HPM if all 5 targets need the healing. It's a little tricky to pick the right times to use it, especially if you're not sure that everyone in the group is 30yds from your target. Like with Circle, your best bet is to target a tank, melee, or yourself. Other healers often position themselves centrally, too, for their own purposes.
If you see that your health is low along with someone else in the raid, it's an ideal time for Binding Heal. Binding Heal also triggers Serendipity, which you can spend on triage GHeals.
Renew is your go-to spell for evening out health discrepancies in the raid, particularly when you're moving a lot or your target is at the edge of your cast range. It's a very quick cast and at 12.5% haste is more efficient than a Greater Heal. If your target isn't about to die, it's a great way to bring someone with low-ish health up to everyone else's level.
Your Holy Word: Sanctuary is targeted at the ground and makes a healing circle for people to stand in. It's generally fairly weak but it's worth doing on fights like Staghelm when people are all stacked in one place. As a rule of thumb, you want 6-7 people standing in your circle for the full duration before it's worth casting.
As of 4.3 Divine Hymn is fantastic group healing on a 3 minute cooldown. Try to use it twice per boss fight.
Tools / Plugins
- Healbot is a great mod for any healer, allowing you to use modified clicks to cast a wide variety of spells directly on a health bar.
- Clique does the same thing but allows you to use the standard blizzard raid frames, or any other raid frame addon.
- Grid is a popular raid frame addon for use with Clique.