With Cataclysm’s release creeping closer, I’ve started rebuilding my personal spreadsheet for my Priest, so I can better understand the spells and talents I’m using. It’s not as advanced as some of the insanely complicated ones you can find out there on the net, but I like having it to tell me:

- Stat conversions (crit rating to crit % or haste to cast time, for example)
- Spell mana costs, cast times and coefficients
- Typical hits, crits, and a weighted average
- Healing per second and healing per mana
- The effect on these values of changing stats, talents or procs

Since I’ve spent the time generating these numbers, I figured I might as well put them up for information purposes. I’ll be doing a bit more conclusion-drawing in a later post, once I’ve had more of a chance to put this stuff into practice.

In the following, all values relate to beta build 12984, and were taken over the last 2-3days on Malevica who at level 85 had approximately 5k SP, 10% crit, 500 haste rating and 750 mastery rating, and a Disc spec with 2% Haste from Darkness (the trees have changed, so the link broke). When Cataclysm goes live you’ll probably have slightly better gear, but the general conclusions will all hold.

**A final reminder that this is beta and all numbers are subject to change.**

#### Stat Conversions

The first thing that’s needed is the set of conversion factors that let you convert ratings into percentages or points (in the case of Mastery):

I generated these by standing around unbuffed and untalented and slowly removing gear to generate a series of data points, and then using a linear regression to extract the conversion factor.

By way of example, here’s a graph of the results for Haste:

Because of the way I chose to plot this graph, the gradient (0.0078055559) of the graph is the haste% per point of haste rating, so the haste rating required for 1% haste is 1/ that value: 1/0.0078055559 = 128.1138733501.

#### Spell mana costs, cast times and coefficients

Now for some information about the spells themselves.

Mana costs are typically expressed within the game as a percentage of base mana, which is your mana pool with no gear or buffs on. (This is what lets the spell costs scale smoothly with your level.)

For a level 85 Priest, base mana = 20590

Using this number, I could work out the baseline (untalented and unglyphed) spell costs, and I also verified them in-game. Here are the current numbers (Blizzard does some funky things with rounding and tooltips so I’ve left the first decimal place for calculation purposes):

Spell coefficients are trickier to get at, and have to be worked out empirically.

When calculating how much a spell should hit for, you take the base heal amount, and add your spellpower modified by another number which can be changed to affect how spells scale with spellpower.

The basic formula is:

Heal amount = Base heal amount + (Coefficient x Spellpower)

Here are the base heal amounts and coefficients I calculated:

These were obtained by standing untalented and unbuffed (except PW:B, for obvious reasons) and recording the average heal amounts at varying spellpower levels. Like with the combat ratings, a linear regression was used to extract the base heal value (the intercept of the graph where SP=0) and coefficient (the gradient of the graph).

Here’s the values in graph format, for those interested:

The scaling on PW:B is a bit odd, since it scales very well with spellpower. That might change as the beta goes along, but remember that having such a long cooldown on a spell allows it to be a bit more highly-powered because it *can’t* end up dominating at high gear levels.

#### Typical hits and crits

Armed with the information above, I was able to work out what a typical heal should land for. In doing this, I have also included the ability to take into account the various talents available and their effects on the spells.

To work out the average hit, I used the following general formula:

Heal amount = [Base heal amount + (Coefficient x Spellpower)] x [1 + (% effect from talent A / 100)] x [1 + (% effect from talent B / 100)] x …

Those “6% increase” type talents are multiplicative, rather than additive, so if you get 6% from Twin Disciplines and 15% from Empowered Healing, you get at 22% increase, not the 21% you might expect (1.06 * 1.15 = 1.219).

At this time I want to say a huge thank you to Blizzard for trimming some of those passive healing increase type talents, it made my life a lot easier!

Anyway, for information purposes, here are the numbers untalented:

And in a typical Disc spec:

In these and the other tables (BT) means the spell is being cast while Borrowed Time is up, (G) refers to either a glyphed version of a spell (Renew) or the glyph component of a spell (PW:S). The numbers in brackets after PoH are the number of targets the spell hits.

What I’ve included in the second table is a column of typical crits (heal x 1.5) and then a weighted average illustrating what all of your casts, a mix of hits and crits, would average out to over time.

These tables are really useful for helping with spell selection. If you have an idea of how much each spell heals for, you’re able to pick the right size for the job, and understand where they fit into the healing toolkit.

#### Healing per second and healing per mana

As well as raw healing amounts, healers also need to know how quickly they can crank out healing with a spell, and how mana-efficient those spells are, especially in Cataclysm.

Here are the values untalented, assuming no crits:

And once again, in a typical Disc spec:

Once again, I’ve added extra columns to the second table. The HPS and HPM columns are based on that weighted average I talked about in the previous section, and should give a better estimate of the HPS and HPM you might achieve if you consider a whole fight.

I’ve not included HPS for PW:B because it’s not a repeatable cast, and I’ve not included HPM for the Glyph of PW:S because it’s essentially cost-free.

I want to have your babies.

I mean…errrr… Yay Discipline numbers!

I read on MMO-C that a new build is due today, so they’re probably out of date already, but it’s a start. And they’re easily enough adjusted now I’ve got the spreadsheet straightened out.

I know a lot of disc priests don’t really use it, but where does binding heal fit in to all of this? Your blog is a recent discovery for me, but it’s definitely bookmarked now 🙂

Keep up the great work!

I’ve added a paragraph to the main post, thanks for the question.

The short version is that BH is more mana and time efficient (better HPS) overall if you use the self-heal component, but if not, since FH hits for a lot more than BH you should use Flash Heal if you’re not injured. BH isn’t a simple “costs twice as much, heals twice as much” button any more.