Defense Rating Formula?

[Tib]

Hey guys, I've been looking for a defense rating formula I can use to find how much defense I need against:

me: lvl 80
mobs: lvl 60, 63, 70, 73, 80, 83

me: lvl 70
mobs: lvl 60, 63, 70, 73

me: lvl 60
mobs: lvl 60, 63

Thanks

[Molohk]

Ratings are different for different levels:
- For a level 60 : 1.5 DR = 1 defense skill
- For a level 70 : 2.36 DR = 1 defense skill
- For a level 80 : 4.92 DR = 1 defense skill

Each point of defense skill above your base defense, decreases your chances to be crit by 0.04%. And, at your level, a mob has a base chance to crit you of 5%. For every level beyond the player, there is an additional 0.2% chance for the mob to critically strike the player. This is why lvl 83 mobs have a 5.6% chance to crit a lvl 80 player, just the same as lvl 73 mobs against lvl 70 players.

From this data, you can infer the defense rating needed to become crit immune at any possible level combination. Keep in mind "boss" level mobs don't have static levels, that means a ZA boss doesn't hit a lvl 80 player like a lvl 63 mob.

[Satrina]

I'm assuming you mean uncrittable here. An equal level opponent has a 5.0% chance to critically hit you. That number goes up/down by 0.2% for every level above/below you. Every point of defense skill reduces the chance of a critical hit by 0.04%.

That means you will always need (5.0/0.04) = +125 defense skill to be uncrittable against an equal level opponent, and (5.6/0.04) = +140 against an opponent 3 levels higher than you. That gets added on to your level maximium defense (5 x Level) or 400/350/300 for 80/70/60, which is where the oft-quoted numbers 540/490/440 come from.

At level 80, a level 70 oppnent has a 5.0 - (10 x 0.2) = 3% chance to critically hit you, and a level 60 opponent has 5.0 - (20 x 0.2) = 1% chance to critically hit you.

The rest is just calculator work from there! (edit: and with Molohk's values for defense rating -> defense skill that I was too lazy to look up, you have everything you need)

[Molohk]

To make it simpler: (player level * 5) + ((((mob level - player level) * 0.2) + 5)/0.04) will tell you how much total defense skill you need to become immune to critical strikes.

You can use the second part of the formula ((((mob level - player level) * 0.2) + 5)/0.04) to figure out how much bonus defense you need, and use the rating conversions above to figure out the exact rating number.

Bah, Satrina beat me :P

[Satrina]

Molohk makes a good point at the end of his first post: The crit chances for 60/63/70/73 vs. 80 are mostly academic since anything that is labelled as a world boss will always attack you as if it were level 83, from Ragnaros to Yogg-Saron.

[Tib]

((((mob level - player level) * 0.2) + 5)/0.04)

Exactly what I was looking for, thank you.

Molohk makes a good point at the end of his first post: The crit chances for 60/63/70/73 vs. 80 are mostly academic since anything that is labelled as a world boss will always attack you as if it were level 83, from Ragnaros to Yogg-Saron.

So I would need defense rating of 540 to avoid being crtically hit by Rag? Or did I misread that? I can't just adjust as if he were a 63 mob? -- which according to that formula would be 40...

[Molohk]

So I would need defense rating of 540 to avoid being crtically hit by Rag? Or did I misread that? I can't just adjust as if he were a 63 mob? -- which according to that formula would be 40...

That is correct, and that is what I ment when I said "boss mobs" don't have static levels. The common theory says that a boss mob will behave as your level +3. This affects the combat table (chances to dodge, parry, miss, crit, etc.) but it doesn't affect how hard it hits you, so being crit by Ragnaros is nowhere near as bad as being crit by KT, so if you must you can afford being crittable when fighting lower level bosses.