Glyphs in Mists of Pandaria saw a complete revamp not just in their interface panel but also in their utility. Prime glyphs were completely removed and most of Major glyphs got a significant nerf in terms of the advantages they offer. While some still offer a straight off bonus (sometimes not even significant enough to justify occupying a Major glyph slot), most of them introduce a trade-off faction which most of the times is hard to calculate. Glyph of Water shield has already caused a lot of controversy between shamans.
I am shamelessly quoting myself from my thread over at Elitist Jerks [Resto] Raid Healing 5.1 MoP :
Water Shield gives you a passive 2138 Mp5, but every time a hit will trigger it you will also gain 2928 mana. If triggered every time on ICD, it would give you an average of 4880 mp5. This is unrealistically high, however. Water shield comes with a glyph that reduces its passive mana regen by 15% reducing it to 1817 mp5. On the same note it will increase its on hit regen by 50% making it 4392 per hit amounting to 7320 mp5. In any fight where water shield reliably triggers more than 2.63 times every 1 minute, this glyph will give you a significant boost in mana regen.
Here comes the interesting part and what causes the controversy among Restos desperately seeking for some extra mana. You would think that Water shield glyph would be mandatory since it only needs to be activated 2.63 per min in order to provide better mana regen. It does right? Right?? Wrong answer. This has been a question I have been asking myself since beta came out. The times WS needs to be activated seem very few, however the number of attacks that actually do that was significantly lowered for Mists. And while still supposedly no AoE will proc it, some still does. And while also supposedly direct damage will proc it,some doesn’t. Blizzard is being very liberal with its boss abilities and the categories they fit. The only way to reliably calculate Water Shield gains ( glyphed or not glyphed ) is by analyzing logs. and therefore putting down once and for all the conundrum of whether Water Shield glyph is useful or not.
For my analysis I used World of Logs and an array of what is mostly my kills and top ranked resto shaman kills. While the number of times that WS activates will vary from fight to fight expect that in the table below the numbers show what is mostly the most efficient way to deal with any boss fight , meaning avoiding all the bad. Some we can’t avoid but for those we can consider for the most part they were avoided for calculating purposes. I want to make the table as fair as possible in respect of boss fights and incoming damage. If you have been hit twice as much in a specific fight shown below, you just tanked the floor for more than you should have. It’s by no means an excuse that Water Shield glyph is better in that specific fight or in general. Getting hit just to activate your WS will get you some mana back but you will most likely be spending it in order to get your HP back up.
You can find the table below in downloadable format at Boss List Water Shield gains – Unglyphed vs Glyphed.