Ciderhelm's Effective Health Theory


Effective Health Theory

Originally posted on the official WoW forums and reposted on TankSpot. This was excavated from an archive made by the Wayback Machine. As such, offsite links will likely not work. Note that this was posted on May 20, 2007 – so it references Burning Crusade talents and builds. Much of it is still applicable to Vanilla though.

Let’s establish what Effective Health and Effective Stamina are. This is basically a measurement of how much raw damage a creature has to deal to kill you. It is a measurement of Armor and it’s relation to Stamina.

What many tanks do not understand is just how much damage a creature is dealing to them. I didn’t realize it until I studied Patchwerk – who dealt 22,000 to 29,000 raw damage to our tanks with every Hateful Strike.

Effective Health is the measurement of how much breathing room your healers have to keep you alive assuming all other factors fail – assuming you do not avoid or block attacks or have a mana shield active. Effective Health is important for tanking heavy hitting creatures because of Murphy’s Law – if you can have long strings of not Dodging an attack, it will definitely happen. Raid tanking, ultimately, is about stability.

Life Per Stamina (LPS) & Effective Life Per Health (ELPH)

  AC                 Mitigation         LPS           ELPH

0 ___________________   0.00% _____    10 : 1 ____  1.00 : 1
10,000 ______________  48.64% _____  19.4 : 1 ____  1.94 : 1
12,000 ______________  53.20% _____  21.3 : 1 ____  2.13 : 1
13,000 ______________  55.18% _____  22.3 : 1 ____  2.23 : 1
14,000 ______________  57.01% _____  23.2 : 1 ____  2.32 : 1
15,000 ______________  58.69% _____  24.2 : 1 ____  2.42 : 1
16,000 ______________  60.25% _____  25.1 : 1 ____  2.51 : 1
17,000 ______________  61.69% _____  26.1 : 1 ____  2.61 : 1
20,000 ______________  65.45% _____  28.9 : 1 ____  2.89 : 1
25,000 ______________  70.31% _____  33.6 : 1 ____  3.36 : 1

The equation to determine Life Per Stamina is (Special thanks to Ilmare):

1 / (1 - Mitigation)

Mitigation is determined through this equation (Special thanks to Satrina):

Mitigation (70) =   -----------------
                     Armor + 10557.5

Mitigation (73) =   -----------------
                      Armor + 11960

Effective Life Per Health is determined simply by dividing the Stamina numbers by 10.

Special Note: Please keep in mind that every 1,000 Armor produces precisely the same increase in Effective Life that the last 1,000 Armor did. Satrina has covered this in-depth, but it can never hurt to say it again – Mitigation is subject to diminishing returns but Armor is not. Armor provides a linear increase in life expectancy. Stamina scales with Armor.

Link to Satrina’s information: The Mathematics of Armour and Diminishing Returns


The first hypothetical is for a tank who has chosen primarily to focus on Stamina and Armor over Avoidance and Defense. The following are reasonable attributes for this Warrior, assuming he has been through Karazhan but not further:
14,000 Armor
13,000 Health

If we run with the above Effective Life Per Health ratio, this is our end result:

13,000 * 2.32 = 30,160 Effective Life

Let’s take the standard number of people who tend to itemize Avoidance and Defense equally, or sometimes in greater standing than Stamina and Armor:
12,000 Armor
12,000 Health

Running the same equation:
12,000 * 2.13 = 25,560 Effective Life

That’s a 5,100 difference in raw damage between two tanks who think they are at similar standing. Or, to put it in more familiar terms, that is the difference between a Warrior comfortably tanking a lvl 70 Patchwerk and a Warrior regularly getting one-shot by same.

Now let’s run some numbers to see how very basic consumables affect tanking. I’ll use just a Flask of Fortification and a Stoneshield Potion on our first tank.
16,000 Armor
14,500 Health

14,500 * 2.51 = 36395 Effective Life

This means that with just these two potions, a tank has increased the damage he is able to withstand more than 17%.


  1. Even though this may sound obvious, it needs to be repeated that every increase in Armor gives linear and potent scaling to the effectiveness of Stamina. Every increase in Armor is a direct increase in the effectiveness of Stamina; every increase in Stamina is a direct increase in the value of Armor.

  2. With the above in mind, the Vitality talent needs to be evaluated for total merit. While a tank may complain that Vitality only gives them a 600 health increase, they fail to recognize the effective health gained is generally going to be more than twice that.

  3. Solid Star of Elune gems should be viewed under the same principle. While Avoidance gems such as +Defense and +Dodge gems will always offer a precise, static damage reduction, a Solid Star of Elune can scale in many raid situations to be the equivalent of over 30 Stamina.

  4. There are a few people who have made comments regarding why Avoidance stats may be better. One poster mentioned that he would rather have 10% Dodge from gems than Stamina. The equivalent of that 10% Dodge would be 2,835 HP, which, given his Armor, would in turn increase his Effective Life by over 6,000. In other words, if he focused on Stamina, he could take hits from a full raid zone beyond his current capability. Need proof? Look at the Armory profiles from tanks in the top-progressing guilds worldwide.

  5. If you have enough Stamina, the most effective means of increasing survivability as a tank is to increase Armor at the cost of other attributes. In particular, when facing an enchant choice such as that of +12 Dodge to Cloak or +120 Armor to Cloak, a Stamina heavy tank will definitely find greater benefit from the +120 Armor.

  6. Increasing Stamina is not always the best method to increase Effective Health. When making a choice between Armor and Stamina upgrades, you will often find that Armor will give you a higher Effective Health than Stamina.

  7. The choices between Stamina/Armor and Defense/Avoidance should only come when evaluating near-equal pieces of gear. Gems are a generally good subject because they are naturally equal in item level. One smaller point to remember is that Avoidance always takes a 7% hit on overall damage reduction due to the combat table – 1% Dodge is actually only 0.93% damage reduction once the additional damage from Crushing Blows is factored in. When dealing with items of significantly different item levels, common sense applies.

  8. It’s not about balance. Like tanking weapons, where faster is always better, when tanking new encounters, Stamina and Armor are always better. The set you use to tank new content should always have the highest Effective Health possible. As you get comfortable with an encounter, you wear more Damage Reduction gear (Armor/Defense/Dodge). This is a hard and fast rule.

In Summary

Like always, this is not written to help the casual tank. It is written only for the tanks who are pushing through content beyond their gear level and wish to do it more effectively. This is what the Stamina Warrior is, and I write this just as passionately as I did over a year ago with “Miles to Go.”

I deeply respect people like Emeraude, who championed the Defense/Avoidance/Agility/Armor tank theory. I remember seeing a great Twin Emperor’s combat monitor from Emeraude. I fall squarely into the Stamina/Armor/Strength/Block Value camp, and many months ago we used to have great arguments on these forums.

I understand the irony of having a Druid post an article about Stamina and Armor. One of the old catchphrases of these forums was that Avoidance is what sets Warriors apart from Druids. I will make this absolutely clear – Avoidance is good (especially Dodge, as Wanderlei has clarified). You will find great pieces of incredible Avoidance gear such as Boots of Elusion. Defense is good. You want and need these stats, and you will get them with much of your tanking gear.

With tanking new content, one rule is important – it’s not about taking less damage; it’s about being able to take more damage.


Addendum (1):

Shield Block Value and additional Effective Health

The Effective Health shown on this website is reliable and accurate. However, there is an additional, scaling bonus to your Effective Health in the form of Shield Block Value. This is the secondary scaling of Shield Block Value (the primary scaling is already included in the equation here).

In addition to increasing your Effective Health by a base amount – exactly like Health – it also decreases a percentage of damage taken. However, the percentage decrease cannot be quantified without detailed information regarding the attack speed, average damage, and maximum damage of your enemy.

Consider the difference between going into a 5-man or Heroic instance with 500 Block Value and going into a fully realized raid boss encounter with same. The percentage reduction – and your total Effective Health – will be different for each encounter. Where you might gain limited advantages to Mitigation against some bosses, others, such as the Prince in Karazhan, will yield far better returns with Block Value. In some cases, especially in world farming, Effective Health can multiply several times over due to a state of near-invulnerability.

Shield Block Value is the stat with the highest potential in the Effective Health equation. It shares a unique relationship with both Health and Armor. Armor is a curved mechanism for increasing Mitigation; Shield Block Value, however, is a linear mechanism for increasing Mitigation. In other words, Shield Block Value does to Mitigation what Health does to Life.

Shield Block Value gains the same benefit as Health when factoring in Armor. As Armor increases, the value of each point of Shield Block Value increases. Then, as the value of Shield Block Value increases from Armor, the value of Health and the impact on Effective Health increases unpredictably – unless we know the incoming damage values.

However, keep in mind how limited Shield Block Value is on gear. Reaching 1,000 Shield Block Value, for instance, is virtually impossible without the use of trinkets or the Tier 5 Shield Block Value bonus. Blizzard most likely itemizes large amounts of Block Rating – a near worthless stat for Warrior raid tanks – to keep item levels and potential Block Value in check. Unfortunately, this also extends to gem choices, and it is this reason – not potential Shield Slam damage – that we are unlikely to see many Block Value gems on the horizon.

Complex? Sure. Bottom line: don’t write Shield Block Value off for it’s Mitigation value.

Thus, Avoidance also helps reliably keep Effective Health high. By increasing Avoidance such as Dodge, you simultaneously decrease the chance of incoming attacks not being avoided or blocked. Indeed, increasing Avoidance will keep more Shield Block charges active for longer, and with enough of it, you become virtually immune to Crushing Blows in most encounters.

This isn’t to say that you need to go gem everything with Avoidance. Please note the wording in bold – it will not increase Effective Health. It will only help stabilize your rate of effective Shield Blocks, which in turn allows Block Value to be reliably factored in. Heavy Avoidance is only important for some boss fights – boss fights you would probably use some Avoidance gear for in the first place. Also, Warrior equipment is already unusually weighted with Avoidance stats, and you gain plenty through normal gearing.

The original thread and all of the outstanding responses can be found here:
WoW Forums -> Effective Health, Armor, and Gemming/Gearing


Exceptions to Stamina Gearing

Posted this to WoW-US forums for easy referencing to all the many threads on the subject… but it may be useful here as well.

This is just a quick-reference set of notes which I’ll probably link people to instead of rehashing all the exceptions to stacking Stamina. Nothing that hasn’t been posted before. If you feel I’ve forgotten to mention something, please comment.

Regarding Stamina/Armor

For new content that the tank is undergeared for – not farm content, and not low-damage content – the Progression Tank:

  • Has high Health/Armor, producing high Effective Health and more steady Rage generation.
  • Does not ignore +Threat stats such as +Hit and +Shield Block Value. Coupled with Health/Armor gearing, the Progression Tank gains significantly more Mitigation benefit from Shield Block Value and more reliable Threat.
  • Uses Rage Efficient talents and understands that most talents have a time and place and specs accordingly.

Why This is “Balanced”

  • Platemail tanking gear is heavily weighted to Avoidance. Gemming with +Stam gems is balancing your gear, which is otherwise imbalanced.
  • Item stats are not equally proportioned by Blizzard; just because an item has equal Item Level does not mean they are equally viable for tanking.
  • With above in mind, Armor/Stamina combinations on items such as rings nearly always provide the a higher percentage in damage you can take than equivalent damage reduction from Avoidance stats.
  • “With tanking new content, one rule is important – it’s not about taking less damage; it’s about being able to take more damage.”

Quick Note on Effective Health

The above is designed around healers, not tanks, as any gearing strategy should be. It is not the most efficient setup, it is the most effective, and easiest to heal.

Exceptions to the Rule:

  • Unusually low Avoidance always warrants more to meet basic uncrushability. Avoidance helps keep Effective Health reliably high.
  • If healers run OOM on a fight, you need more Avoidance.
  • Fast, low-damage mobs always favor Avoidance, such as Prince.
  • Socket bonuses such as Khorium Destroyer’s +3 Stamina are better served with mixed gems.
  • Slow progression or exceptional/neurotic healers warrant heavier Avoidance.
  • All fights have Effective Health minimums that, once safely met, do not need more Armor/Stamina.
  • All content that you’ve already completed warrants further gear improvements in Avoidance and Threat, not Effective Health, as you’ve already proven you’ve met that standard.

Can Avoidance Tanks be Successful?

  • Sure, some Avoidance gemming and gearing won’t destroy all progress. As long as their item levels stay up to par with the content, they’ll be able to successfully get through content. Stamina gearing is min/maxing, not a necessity.
  • With the above in mind, Paladin tanks are also viable through the entirety of raiding, barring gimmick fights.

Final Note on Stamina Gearing:

  • Effective Health sees relatively little gain pre-buffs moving from Karazhan to Black Temple. With the exception of T5, gains are heavier in Threat/Avoidance.
  • Stamina gearing is not new to TBC – we’ve been having this debate on these forums since Molten Core. It just became really obvious in Naxxramas/TBC that Blizzard was moving to favor Effective Health tanks.

Different Gear for Different Encounters

  • Have a variety of gear, particularly rings and trinkets, that can be switched and customized to the fight. More Armor/Stamina is not the solution to every encounter.
  • Generally, Effective Health/Block Value gear is best for handling non-raid content while wearing raiding gear.

Gilded Thorium is better than Devilshark in nearly all situations; in situations where Threat is more important, Farstriders is better than Devilshark.

Virtually any level 70 epic shield is better than Crest of Sha’tar; S2 Arena shield is better than all pre-Hyjal shields.

Quick Note on Block Rating

  • As many posters correctly point out, Block Rating does not increase uncrushability and should not be stacked at the expense of other stats.
  • However, Block Rating always provides a benefit in overall damage reduction. If you have some on your gear, don’t sweat it.