Every week, WoW Insider brings you Spiritual Guidance for discipline, holy and shadow priests. On Wednesdays, shadow priesting expert Fox Van Allen comes from out of the shadows to bask in your loving adoration.

I get a lot of email at my WoW Insider account. Granted, most of the emails I get are intriguing business deals from the African continent. But I get real mail too, and lately, I've been getting a lot of mail about our four-piece tier 13 bonus.

Oh, no! My Tier 13 four-piece bonus isn't as good as I thought it would be! My wallet's too small for my fifties, and my diamond shoes are too tight!

Signed,
Everyone

I haven't answered the mail publicly yet, because I couldn't imagine the concerns being valid. After all, could it really be worth it to keep two-piece tier 12 over four-piece tier 13? But with so many of you concerned ... hey, maybe there's something to this. Maybe it is worth keeping your two-piece tier 12.

I decided sit down with a pen and paper and find out for myself.

The two-piece tier 12 bonus

Without a doubt, the two-piece T12 bonus is absolutely great -- so great, in fact, that a lot of shadow priests pause about giving it up. That's totally understandable. But is it good reasoning?

Let's start by analyzing exactly what the two-piece T12 bonus does to our DPS. For the uninitiated, the bonus is:

While you are in Shadowform, your Shadowfiend deals 20% additional damage as fire damage and its cooldown is reduced by 75 seconds.

That's really compelling. Normally, the Shadowfiend is a 4-minute cooldown (when properly talented), with 10 seconds being knocked off the cooldown timer with each crit. This bonus reduces that base cooldown to 2 minutes, 45 seconds.

At first blush, the 75-second cooldown reduction sounds quite impressive. But the value of the two-piece tier 12 bonus is tempered by the Sin and Punishment talent. After all, any Mind Flay crit during those extra 75 seconds immediately reduces the waiting period.

But don't take my word for it. I dug through Simulationcraft numbers for a shadow priest with the tier 12 bonus and a shadow priest without the tier 12 bonus. The results may surprise you:

• With two-piece T12, Shadowfiend was up 30% of the time, doing 12,061 DPS during that time.
• With four-piece T13, Shadowfiend was up 24% of the time, doing 10,397 DPS during that time.

Tier 12 gives you more uptime, and thanks to the 20% buff to Shadowfiend damage, more DPS when it's up. Multiplying the numbers above together, we find that with a T12 bonus, the Shadowfiend contributes 3,618 DPS to our overall total. Without the bonus, the Shadowfiend contributes 2,495 DPS. The two-piece tier 12 bonus is thus worth about 1,123 DPS.

The four-piece tier 13 bonus

Part of why the two-piece tier 12 bonus seems so great is because the four-piece tier 13 bonus seems comparatively weak -- or, at the very least, incredibly difficult to wrap your head around:

Your Shadowfiend and Shadowy Apparitions have a 100% chance to grant you 3 Shadow Orbs each time they deal damage.

How the heck do we calculate the value of that? Well, again, Simulationcraft comes to the rescue. For those with the four-piece Tier 13 bonus, the majority of Mind Blast casts -- a full 69% of them -- are fired off under the influence of 3 Shadow Orbs. By comparison, without the bonus, only 35% of casts have the benefit of 3 Shadow Orbs. That's a pretty sizable difference.

If you want some harder DPS number, relax. Simulationcraft has those as well. Compare:

MB Shadow Orbs	Total contribution to DPS (w 4pc T12)	Total contribution to DPS (w 4pc T13)
0	499	640
1	1,283	463
2	1,740	645
3	2,487	5,605

Summing the two columns, we find that Mind Blasts add about 6,009 DPS to our total when we're wearing four-piece tier 12 and about 7,353 DPS when we're wearing four-piece tier 13. But before we do a simple subtraction to find the value of the four-piece tier 13 bonus, let's remember that four-piece tier 12 bonus actually boosts Mind Blast damage by 15%. Subtracting that 15% from the 6,009 DPS we see with four-piece T12 gives you a two-piece T12 value of 5,225 DPS.

Now we can do our simple subtraction. The four-piece tier 13 bonus is thus worth about 2,128 DPS.

Maximizing the value of your T13

We've just numerically proven that tier 13 is better than tier 12. But what's this? You say, "But Fox, it just doesn't seem like I'm getting that much out of my four-piece tier 13!"

Well, shut up, stupid, you're wrong. I mean, uh ... wait, no. I respect your opinion, but ... um ... you just need to learn how to squeeze the juice out of your T13. And the best way to do that is to move.

Yup, seriously. It's that easy. Move.

Obviously, you can't be moving all the time. After all, we've got Mind Flay, Mind Blast, and Vampiric Touch to cast. But all our other important casts, Devouring Plague, Shadow Word: Death, Shadowfiend, and Dark Archangel are instant spells that we can hit on the go. It's a hassle, no doubt, but the simple act of moving changes the odds that your ticks of Shadow Word: Pain will generate a Shadowy Apparition and thus 3 whole Shadow Orbs, from a lowly 12% to a whopping 60%.

Believe me, moving so frequently feels weird. I'd even go as far as to say it feels wrong. But whenever it's time to fire off an instant-cast spell, move. Keep moving until you're ready to cast something that isn't an instant-cast. This works well when your opponent is under 25%, and you can use Shadow Word: Death twice in a row -- a good 2 to 3 seconds' worth of movement.

So get a move on, shadow priests. The sooner you learn how to cast on the fly, the sooner you'll drive your DPS into the stratosphere.

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