Why you shouldn’t use Glyph of Water Mastery

Recently, an article was posted on WoW.com (formerly WoW Insider) discussing builds for healing shamans. The article erroneously recommended many times that it’s beneficial to use the Glyph of Water Mastery for a number a situations. This caused a bit of an uproar in the comments, and I also sent a tweet to @wowinsider calling them out¹. They were kind enough to reply asking what specifically I disliked about their article, and while I did reply (see here, here and here), I felt like I could provide more information than Twitter will allow.

The Math-y Portion

The Glyph of Water Mastery modifies your Water Shield to provide 30% more passive mana regeneration. At level 80, we have Rank 9 of Water Shield, which provides 100 mana per 5 seconds passively. This means that the glyph adds 30 MP5. To put this into context, there are many items dropped in heroics that provide around 20 to 30 MP5 on it (here is a quick wowhead search of mail items with MP5, limited to the original heroics that Wrath of the Lich King provided).

To prove my point, let me show you some math on why this is such a lackluster benefit. First, let’s establish where MP5 is helpful to us: During boss fights. Outside of boss fights, it’s much easier to regenerate mana, since we can drink and tend to have more mana regen when not casting. During a boss fight, however, we can’t drink to regenerate mana and can only use one potion, as well as various talents and skills to gain mana. Further, MP5 is a ratio with units of time, so we can say that the longer a fight lasts, the more mana we will regenerate. Lets say a boss fight will last five minutes; a fairly average length for calculations. There are 300 seconds in 5 minutes, but we’re in units of 5 seconds, so we will get that 30 mana  60 times during that boss fight, adding up to 1800 mana (the math: 5minutes * 60seconds / 5seconds * 30mana = 1800).

On the other hand, a Runic Mana Potion would provide at least 4200 mana in that fight. Another consideration is that the Insightful Earthsiege Diamond—the meta gem recommended for Shamans to use—will be providing about 50MP5², adding up to about 3000 mana for the same fight.

But we can go further and even show how other glyphs can provide more mana than the Glyph of Water Mastery. How does this work, when no other glyph effects mana regeneration? Consider glyphed Lesser healing wave.

Lesser Healing Wave uses 659.4 mana at level 80 and heals for 1606 to 1834—or on average it heals for 1720. It’s spell power coefficient is 80.57% (90.57% with Tidal Waves), meaning 90.57% of your spell power will be added to the amount you heal with this spell. It would be reasonable to assume that even a fresh level 80 can have at least 1000 spell power, so my calculations will use that number. That means that your LHW should be healing for about:

1720 + (1000 * .9057) = 2625.7 hp

Now, we can look at the amount of mana used per health point, simply by dividing the 659.4 mana used to cast that by the 2625.7 hp that it provided, giving .251 mana per health point (the math: 659.4mana / 2625.7hp = .251mana/hp). Next, if we were to glyph LHW, it would be 20% more effective, yielding:

2625.7 hp * 1.2 = 3150.84 hp

Or, 525.14 health points more for the same amount of mana used (the math: 3150.84 – 2625.7 = 525.14). If we want to figure out how much that amount of hp is in terms of mana, we use our mana/hp ratio. Multiplying the ratio by hp will cancel out that unit, leaving only mana remaining. Here’s the math:

525.14 hp * .251 mana/hp = 131.81 mana

What does this mean? Every time you cast a glyphed Lesser Healing Wave (assuming no overheal), you are using about 132 mana less than the same spell without a glyph. Since you can cast LHW at least three times in a 5 second period, that could add up to over 396MP5.

Now of course all this math is theoretical and the results all depend on the fight and what you are doing during that fight, but the point is that the Glyph of Water Mastery is provably outpaced by many other things in terms of mana.

When is the Glyph of Water Mastery worth using?

Simply, when leveling. More mana regeneration means less stopping to regenerate mana, complicated by low level shamans having less tools for mana regen and gear providing less MP5 at lower levels.

1: I also called them out for their hunter column, which Rilgon at Stabilized Effort Scope does a much better job of. He may do so with more rage than I think is necessary, but he justifies himself with cold hard math; I definitely respect his opinion on hunters.

2: Experience provides MP5 values as shown in the table here for the IED meta gem. As a shamans haste goes up, so will the MP5 of the gem, but 50MP5 is by far a reasonable estimate, also used here.