Note from the author: Sorry about the lack of posts. Plants vs Zombies has eaten up a lot of my free time. It's that addictive.
With the advent of the Glyph system in 3.0 and the new glyphs in 3.1, there's been quite a bit of talk as to the Major Glyphs to use for PvPers of all classes. There are a number of excellent Major Glyphs that are consideration worth for Discipline Priests, so let's work our way through them.
Glyph of Penance: Reduces the cooldown of Penance by 2 sec.
If you're a Discipline Priest in PvE or PvP, this glyph is an absolute must have. Penance, with a 10 second cooldown, goes down to 8 seconds with the glyph. With 2/2 Aspiration, this 8 second cd goes down by another 20%, to 6.4 seconds. In many BG's and Arenas, the Priest is horribly trained upon by melee and anything to help them stay up like the now self-castable Penance is a huge help for personal survivability.
Glyph of Pain Suppression: Allows Pain Suppression to be cast while stunned.
This is another outstanding glyph considering two things: 1) the amount of burst damage a team can dish out and 2) the number of stuns present in the game. In 3's and 5's it's invaluable as most teams will play a cc game on healers over focusing them as the main target. Either way, however, this glyph will save your butt and you will be glad you had it.
Glyph of Inner Fire: Increases the armor from your Inner Fire spell by 50%.
This is an excellent mitigation glyph as it increases your armor against physical damage by a pretty huge amount. As Inner Fire is no longer dispellable, if you find yourself constantly trained by melee and your teammates aren't peeling well enough such that you fall behind on healing/mana, consider this glyph.
Glyph of Power Word: Shield: Your Power Word: Shield also heals the target for 20% of the absorption amount.
This glyph is a great utility glyph. With the new talent Soul Warding, chain bubbling people is a great way to mitigate alot of incoming damage and provide a minor heal at the same time. If you find that you bubble multiple targets alot or your teammates aren't great at playing defensive, give this glyph a look.
Glyph of Dispel Magic: Dispel Magic spell also heals your target for 3% of maximum health
This glyph used to be the go to glyph, as it is similar to the Glyph of Power Word: Shield. Unfortunately, while PW:S is quite consistent in it's utility, pure throughput (offensive/defensive) has become far more desirable than a possible heal off of a defensive dispel. Furthermore, as cleave teams become far more prevalent, spending a GCD on a defensive dispel isn't going to be that great, as only one melee puts up enough magic debuffs to warrant this glyph (Ret Paladin).
Glyph of Smite: Smite spell inflicts an additional 20% damage against targets afflicted by Holy Fire.
The premire glyph for Priests that play in a comp that has enough control or damage avoidance to allow them to nuke. Primary comp partners are Rogue and Mage. With this glyph, Smite becomes a very legitimate threat, often pumping out 4k+ of holy damage. With Focus Magic and/or Tricks, the Priest essentially becomes a DPS class when needed.
Glyph of Renew: Reduces the duration of your Renew by 3 sec. but increases the amount healed each tick by 25%
This is an underappreciated glyph, as it is generally outshone by other defensive glyphs. However, the additional healing is quite consistent, which, if it is kept on multiple targets, can help mitigate aoe DPS such as Affliction Warlocks and Death Knights.
Glyph of Mass Dispel: Reduces the mana cost of Mass Dispel by 35%
Unfortunately, this glyph was recently nerfed from a 50% mana cost reduction to 35%. Back in it's previous state, it was a wonderful tool in 5's to strip an entire team of buffs for less than the cost of a Dispel Magic. Sadly, with the nerf, the utility of this Glyph has pretty much gone down the toilet.
So, which glyphs am I using? Well, as a Discipline Priest, I have to go with the Glyph of Penance because it's just sheer awesomeness. The other two glyphs are really the ones up for debate. Personally, I prefer the Glyph of Pain Suppression and either the Glyph of Power Word: Shield and the Glyph of Inner Fire. I was a skeptic of Glyph of Pain Suppression for a while until it started paying off in spades across multiple brackets. In 2's I'm often focused by double DPS teams, of which 99% of them feature a Rogue. In 3's and 5's, I'm more likely to be cc'd, but swaps to me do happen quite frequently. If I can Pain Suppression the first coordinated nuke, Hand of Protection usually helps me survive the second and either we win because the opponents have just used 2 sets of offensive cooldowns, or the match lasts long enough that either Pain Suppression comes back up, or I run oom. When looking at most of the top teams, it becomes apparent that many have a stun that is either used to cc me or to bring me down in a coordinated burst: Charge, Intercept, Kidney Shot, Gnaw, HoJ, Deep Freeze, Shadowfury, Intimidate, etc. The list goes on and on.
As for the last glyph, it really depends on the trend of melee and how well your teammates peel. If melee starts stacking Armor Penetration, the additional armor provided by the Glyph of Inner Fire may prove to be useless. Warriors using Grim Toll have given me problems as they bring me down to zero armor in a hurry. I usually bite it once Pain Suppression and Hand of Protection are down. In this case, a passive healing glyph like Glyph of PW:S may be better as it can give you a little bit of a boost to keep the target away from Execute range as you set up your next heals. If your teammates can peel very well, you may not need the extra armor from Glyph of Inner Fire as it is likely that your PW:S will last longer. In nearly all cases, avoidance is better than mitigation.