Regarding Hold the Line and Parry.

I see a lot of players saying “Reforge to get more Parry than Dodge because it is better due to Hold the Line procs.”

At first glance that makes sense, as there are no talents that take of advantage of Dodge over Parry, while HtL takes advantage of Parry over Dodge.

I admit I was dubious at first if increasing your chance to Parry really made a noticeable difference in HtL uptime.

So, I wanted to figure out how much HtL uptime was gained by adding more Parry. Turns out, I think I was both right, and wrong.

The formula I used is the same used for calculating Flurry uptime for Fury Warriors (very similar mechanic) – found here http://elitistjerks.com/f81/t22705-dps_compendium/

As is said in the EJ post, and I will restate here; that is not an exact formula for uptime. But it’s pretty darn close.

We’ll use that formula for calculating HtL uptime.

Where P = Parry chance and A = the number of attacks you will receive while the HtL buff is active.Code:`1–(1–P)^A`

We assume a 2.0 attack speed for bosses in most all other formulas, so we assume the same here. You’ll get hit 5 times during a HtL proc, so A = 5.

Just sub in P for varying amount of Parry, and we get this chart for uptime:

(Note: numbers are rounded to the nearest hundredth of a percent)

Explanation of columns:Code:`Parry % HtL uptime%: Uptime (sec) Extra time Parry Rating Rating/P% Parry/HtL%`

10 40.95 122.85 10.06 230 49 14.63

11 44.16 132.48 9.63 279 50 15.58

12 47.23 141.69 9.21 329 52 16.94

13 50.16 150.48 8.79 381 53 18.09

14 52.96 158.88 8.4 434 54 19.29

15 55.63 166.89 8.01 488 56 20.97

16 58.18 174.54 7.65 544 57 22.35

17 60.61 181.83 7.29 601 59 24.28

18 62.93 188.79 6.96 660 61 26.29

19 65.13 195.39 6.6 721 62 28.18

20 67.23 201.69 6.3 783 63 30

21 69.23 207.69 6 846 66 33

22 71.13 213.39 5.7 912 67 35.26

23 72.93 218.79 5.4 979 69 38.33

24 74.64 223.92 5.13 1048 72 42.11

25 76.27 228.81 4.89 1120 73 44.79

26 77.81 233.43 4.62 1193 76 49.35

27 79.27 237.81 4.38 1269 78 53.42

28 80.65 241.95 4.14 1347 80 57.97

29 81.96 245.88 3.93 1427 83 63.36

30 83.19 249.57 3.69 1510 NA NA

Parry%- Parry chance (note1)

HtL uptime– The average uptime of Hold the Line, using the above formula

Uptime (sec)– The uptime of Hold the Line in a 5 min fight.

Extra time– How many additional seconds of Hold the Line uptime are gained compared to the previous Parry chance

Parry Rating– How much Parry rating is needed to get this much Parry chance

Rating/P%- How much Parry rating is needed to get an additional 1% Parry chance

Parry/HtL%- How much Parry rating is needed to increase Hold the Line’s uptime by 1%

Note1: This would be your "absolute" or actual Parry chance, which isn't necessarily what your character sheet displays. All other numbers reflect character sheet numbers.

One thing that I noticed though was how much uptime is actually gained when you put it into secs of combat. While going from 10% Parry to 11% Parry gives over 3% more HtL uptime over the course of the fight. But, that only translates to about 9.6 secs – or about 1 full HtL proc. Offensively, this translates to about 6.5 GCDs, and up to 3 Heroic Strikes (if you’re HSing every 3 secs), for 9 total additional attacks with +10% crit by increasing your Parry chance by 1%.

Defensively that comes out to just shy of 5 boss swings with an additional +10% Crit Block rate. (From here you figure out your chance to get a crit block within those ~5 attacks, which varies depending on your Mastery skill.)

As you can see from the chart, HtL uptimes gains from additional Parry are subject to diminishing returns – which is to be expected given we are using the same formula for Flurry, which has diminishing returns on additional crit. Going up to 25% Parry (which I’m guessing most tanks have in WotLK now), only about ½ of a full HtL proc is gained. That comes out to 3 GCDs, plus 1 HS, and about 2 boss swings with the additional Crit chances (offensive and defensive). Not only is it difficult to increase your Parry chance by 1% at this level, but when you do, the gains are likely not worth it (4 attacks and 2 boss swings)