Here is a very important article by community author Satrina regarding threat generation come 3.0 and WotLK that is core reading for Prot War tanks:

(Check the original thread for the most up-to-date data)

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Thanks to the built-in threat functions, getting innate values is a whole lot easier for 3.0. I wrote myself a little addon to pop threat numbers up after I hit things and went to work with a spreadsheet. I started out with no talents spent and did the trained abilities first, then went and spec'd deep protection. Then went and respec'd deep protection since Damage Shield is cool and all, but a pain in the ass to account for all the little blips of extra damage. I did all tests at different attack power values to see if there was any scaling going on. I won't put the numbers for every last test I did, just a sample for each ability to illustrate.

To get innate threat values, I take the threat given by the UI and divide by 207.3 to normalise the threat to be independent of stance. I remove any white damage done, and the damage done by the ability being tested if any. The resulting amount is the innate threat. Where applicable, we'll tie that back to AP if it scales on it, note that it's a flat value, or if it's a multiplier (there are still a lot of flat value innate threat numbers).

Note that in our original threat estimations (that we use now in WoW 2.0), we equated 1 damage to 1 threat, and used 1.495 to represent the stance+defiance multiplier. We see that Blizzard's method is to use the multiplier without decimals, so in 2.x it would've been x149 (maybe x149.5); it is x207 (maybe 207.3) in 3.0. I expect that this is to allow the transport of integer values instead of decimal values across the Internet for efficiency. It appears that threat values are multiplied by 207.35 at the server, then rounded.

Big news #1: Devastate still applies Sunder Armour. However, you no longer get the threat from the Sunder that was applied. You get the threat from the damage dealt by the Devastate plus 5% of your attack power as threat.

Big news #2: You gain 207 threat whenever you dodge, parry, or block an opponent's attack when in defensive stance. You generate no threat for dodge, parry, or block in battle stance or berserker stance.

This isn't complete yet. I'll backfill with new numbers as I get them.

A summary! These are for a level 80 character.

Stance modifiers:

Battle Stance ______________________ x 80

Berserker Stance ___________________ x 80

Defensive Stance ___________________ x 207.3

Innate threat values:

Cleave _____________________________ 225 (split)

Concussion Blow ____________________ 0 (damage done only, stance modifier is applied)

Damage Shield ______________________ 0 (damage done only, stance modifier is applied)

Devastate __________________________ 5% of AP (threat from Sunder is not gained)

Dodge/Parry/Block___________________ 207 (defensive stance only, stance modifier is not applied)

Heroic Strike ______________________ 259

Heroic Throw _______________________ 1.5 x damage

Revenge ____________________________ 1031

Shield Bash ________________________ 36

Shield Slam ________________________ 770

Shockwave __________________________ 0 (damage done only, stance modifier is applied)

Spell Reflect ______________________ 0 (damage done only, stance modifier is applied)

Social Aggro _______________________ 0

Sunder Armour ______________________ 438

Rage Gain. This is a special case. Gaining a point of rage generates 500 threat, but does not get multiplied by the stance modifier. This does not make it more powerful than Sunder Armour. A Sunder in defensive stance would be multiplied by 207.3, yielding 90797 threat, whereas a point of rage always generates 500 threat.

Calculations follow, below. If you see anything that I've done wrong, let me know so I can fix and/or re-test.

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(Note that in some cases I left my shield on, so rage gain from Shield Specialisation varies the threat numbers a very small amount off of the "perfect" number.)

Social Aggro

Gives zero threat.

Rage Gain

One point of rage generated gives 500 threat. This is not multiplied by the stance multiplier. This is not better than Sunder Armour, which at 438 normalised threat, yields 90797 threat in defensive stance. Rage always gives 500 threat.

Defensive Stance

Verifying others' findings, I hit some mobs a few times in defensive stance to get the defensive stance modifier:

452 damage creats 97322 threat. The defensive stance modifier is 207.3

(The modifier for battle stance and berserker stance is 80)

Damage Shield

Generates no innate threat, just the threat from damage done (modified by stance)

Revenge

2618AP: 0 melee damage, 623 revenge damage, 342956 threat. Normalised threat is 1654, and removing (623) damage leaves 1031 innate threat

2076AP: 525 melee damage, 631 revenge damage, 453681 threat. Normalised threat is 2188, and removing (525 + 631) damage leaves 1032 innate threat(!)

2044AP: 984 melee damage, 687 revenge damage, 560258 threat. Normalised threat is 2702 and removing (984 + 687) damage leaves 1031 innate threat

We conclude that Revenge has a flat 1031 innate threat, independent of AP.

Heroic Throw

Heroic throw is nice because the mob has to run to you, so the threat number gets updated without any melee hits. Too easy!

2618AP: 1700 throw damage, 528742 threat. Normalised threat is 2550, and removing (1700) damage leaves 304 innate threat

2044AP: 609 throw damage, 189414 threat. Normalised threat is 913 and removing (984 + 687) damage leaves 850 innate threat

1916AP: 579 throw damage, 180084 threat. Normalised threat is 868 and removing (984 + 687) damage leaves 289 innate threat

We see that Heroic Throw doesn't use a flat modifier. If we do this, though:

2618AP: 1700 throw damage, 528742 threat. Normalised threat is 2550, and dividing by damage done (1700) we get 1.50

2044AP: 609 throw damage, 189414 threat. Normalised threat is 913 and dividing by damage done (609) we get 1.50

1916AP: 579 throw damage, 180084 threat. Normalised threat is 868 and dividing by damage done (579) we get 1.50

We conclude that Heroic Throw generates 150% of damage as threat.

Sunder Armour

I was lazy and didn't mouseover, so we'll just remove the threat done by the melee hit that came with the sunder:

2618AP: 971 damage, 292260 threat. Normalised threat is 1409, and removing 971 damage leaves 438 innate threat

2044AP: 432 damage, 180498 threat. Normalised threat is 870, and removing 432 damage leaves 438 innate threat

1916AP: 831 damage, 263231 threat. Normalised threat is 1269, and removing 831 damage leaves 438 innate threat

We conclude that Sunder Armour has a flat threat value of 438.

Shield Bash

Shield bash hits pretty hard now, which is neat. Just two tests at different AP since I wasn't expecting much change:

2618AP: 460 damage, 102845 threat. Normalised threat is 496, and removing 460 damage leaves 36 innate threat

2044AP: 432 damage, 97039 threat. Normalised threat is 468, and removing 432 damage leaves 36 innate threat

We conclude that Shield Bash has a flat 36 innate threat, independent of AP.

Heroic Strike

I just let the mob beat on me until I had rage to HS, then recorded the value. No extra melee hits.

2618AP: 813 damage, 222280 threat. Normalised threat is 1072, and removing 813 damage leaves 259 innate threat

2044AP: 796 damage, 218755 threat. Normalised threat is 1055, and removing 796 damage leaves 259 innate threat

1916AP: 733 damage, 205692 threat. Normalised threat is 992, and removing 733 damage leaves 259 innate threat

We conclude that Heroic Strike has a flat 259 innate threat, independent of AP.

Cleave

As with Heroic Strike.

One target:

2618AP: 577 damage, 166295 threat. Normalised threat is 802, and removing 577 damage leaves 225 innate threat

Two targets:

2618AP - Target 1: 570 damage, 141516 threat. Normalised threat is 682.5, and removing 570 damage leaves 112.5 innate threat

2618AP - Target 2: 1201 damage, 272354 threat. Normalised threat is 1313.5, and removing 1201 damage leaves 112.5 innate threat

We conclude that Cleave has a flat 225 innate threat, independent of AP. If there is one target, the full 225 is applied to it. If two, half of the 225 is applied to each.

Shield Slam

Beat up one mob, then move to another and slam it in the face. A melee attack usually slipped in, so we'll account for it.

2618AP - 548 melee damage, 2648 shield slam damage, 822350 threat. Normalised threat is 3966, and removing (548 + 2648) damage leaves 770 innate threat

2408AP - 0 melee damage, 2396 shield slam damage, 656470 threat. Normalised threat is 3166, and removing 2396 damage leaves 770 innate threat

2204AP - 465 melee damage, 2432 shield slam damage, 760352 threat. Normalised threat is 3667, and removing (465 + 2432) damage leaves 770 innate threat

2048AP - 1005 melee damage, 2596 shield slam damage, 906327 threat. Normalised threat is 4371, and removing (1005 + 2596) damage leaves 770 innate threat

We conclude that Shield Slam has a flat 770 innate threat, independent of AP.

Shockwave

Beat up one mob, then move to another and boom.

2204AP - 1080 shockwave damage, 223939 threat. Normalised threat is 1080, and removing 1080 damage leaves 0 innate threat

2048AP - 1206 shockwave damage, 250064 threat. Normalised threat is 1206, and removing 1206 damage leaves 0 innate threat

We conclude that Shockwave has no innate threat component.

Concussion Blow

2618AP - 515 melee damage, 1007 c.blow damage, 315586 threat. Normalised threat is 1522, and removing (515 + 1007) damage leaves 0 innate threat

2204AP - 493 melee damage, 2104 c.blow damage, 538488 threat. Normalised threat is 2597, and removing (493 + 1206) damage leaves 0 innate threat

We conclude that Concussion Blow has no innate threat component.

Devastate

I am still testing to confirm 100% but it appears that in WoW 3.0 Devastate applies the Sunder Armour debuff but does not give the threat for it. You gain only the threat from the damage done by the Devastate, plus the innate threat (see below).

One Devastate:

2608AP - 600 melee damage, 535 devastate damage, 262711 threat. Normalised threat is 1266, and removing (600 + 535) damage leaves 132 innate threat

2054AP - 535 melee damage, 491 devastate damage, 233891 threat. Normalised threat is 1128, and removing (535 + 491) damage leaves 102 innate threat

2466AP - 663 melee damage, 1244 devastate damage, 420920 threat. Normalised threat is 2030, and removing (663 + 1244) damage leaves 123 innate threat

Clearly, the innate threat is not a flat value. Looking at it this way, though:

2608AP - 132 innate threat is 5% of 2608

2054AP - 102 innate threat is 5% of 2054

2466AP - 123 innate threat is 5% of 2466

We conclude that the first Devastate you apply has innate threat equal to 5% of your AP.

Two Devastates:

2626AP - 1194 melee damage, 2480 devastate damage, 815714 threat. Normalised threat is 3934, and removing (1194 + 2480) damage leaves 260 innate threat

2048AP - 933 melee damage, 881 devastate damage, 418640 threat. Normalised threat is 2019, and removing (933 + 881) damage leaves 205 innate threat

We see that the innate threat values are 10% of the AP values. However, there are two Devastates in this test, and so each Devastate had 130/102 innate threat.

We conclude that the second Devastate you apply has innate threat equal to 5% of your AP.

Three Devastates:

2616AP - 1878 melee damage, 2969 devastate damage, 1086304 threat. Normalised threat is 5238, and removing (1878 + 2969) damage leaves 392 innate threat

2206AP - 1154 melee damage, 1757 devastate damage, 673434 threat. Normalised threat is 3248, and removing (1154 + 1757) damage leaves 337 innate threat

We see that the innate threat values are 15% of the AP values. However, there are three Devastates in this test, and so each Devastate had 130/112 innate threat.

We conclude that the third Devastate you apply has innate threat equal to 5% of your AP.

Four Devastates:

2616AP - 2021 melee damage, 3804 devastate damage, 1316047 threat. Normalised threat is 6347, and removing (2021 + 3804) damage leaves 522 innate threat

2206AP - 2385 melee damage, 2817 devastate damage, 1170474 threat. Normalised threat is 5645, and removing (2385 + 2817) damage leaves 440 innate threat

We see that the innate threat values are 20% of the AP values. However, there are four Devastates in this test, and so each Devastate had 130/110 innate threat.

We conclude that the fourth Devastate you apply has innate threat equal to 5% of your AP.

Five Devastates:

2616AP - 3459 melee damage, 4342 devastate damage, 1752933 threat. Normalised threat is 8453, and removing (3459 + 4342) damage leaves 652 innate threat

2490AP - 4189 melee damage, 2952 devastate damage, 1609242 threat. Normalised threat is 7761, and removing (4189 + 2952) damage leaves 620 innate threat

We see that the innate threat values are 25% of the AP values. However, there are five Devastates in this test, and so each Devastate had 130/124 innate threat.

We conclude that the fifth Devastate you apply has innate threat equal to 5% of your AP.

We conclude that all applications of Devastate get innate threat equal to 5% of AP.

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Spell Reflect

Defensive Stance: Reflected 836 damage spell, gained 173345 threat. 836 x 207.35 = 173345

Battle Stance: Reflected 793 damage spell, gained 63440 threat. 793 x 80 = 63440

We conclude that spell reflect generates threat equal to the damage reflected, and the the stance modifier is applied.