Titan Quest Shield Block Formula Guide by Xaece

I found the formulas for Shield Blocking. Melee Blocks are in fact based on DA partially, and Dex partially. I am making an excel sheet, stay tuned for more info on how the following work out.

ToHit Formula
( ((offensiveAbilityDV 3) + 3000) – (defensiveAbilityDV 3) ) 30

‘Actual’ Chance ToHit Formula (Takes the above formula)
((probabilityToHitDV 2) + 45) 100

MeleeBlock Formula (Uses the ToHit Formula, not the ‘Actual’ Chance ToHit Formula)
(blockChanceDV + blockChanceModifierDV) – ((probabilityToHitDV – 100) 0.5)

ProjectileBlock Formula (Does not use a Formula within, just total Dex)
(blockChanceDV + blockChanceModifierDV) ((dexterityDV 1000) + 1)

New Information
Every 50 more DA you have over your attacker, that attacker has a 5% chance less to hit you. 550 DA vs 500 OA, 150 DA vs 100 OA, and 1050 DA vs 1000 OA this is all consistent across.

Every % Chance below (or above) the chance to hit, there is half that chance change added to your melee block ratio. For example. If you have 50 more DA than your attack, your attack has a 95% chance to hit, which is 5% chance to miss. Half that 5% is 2.5% which is added directly to your chance to block Melee attacks. (That 95% chance to hit has one more modifier to run through before its the ‘Actual’ chance to hit). After it goes through the ‘Actual’ ToHit Formula, essentially the miss chance is from above is halved and an additional 5% is added to it. So, at same OA and DA, there is an ‘Actual’ 5% Chance to Miss, with 50 more DA than OA, there is an ‘Actual’ 7.5% Chance to Miss)

Every 100 Dex increases your chance to block Projectiles by 10%. If you have a 30% chance to bock (after mods), then your chance is now 33%. This means, with 1000 Dex, and 50% chance to block you will always block Projectiles (so long as the shield recovery isn’t cooling down).

What this all means, is against Archers, no amount of DA will help you, and only Dex and higher Block Chance will (This includes +Block Chance mods!). However, it is far easier to get high base Block rates than it is to get lots of Dex. Seeing as Dex only adds 1 DA for the Melee Block rate, this enforces, IMO, that increasing your base block rate is far more important than high Dex.

If you are recieving Crits (from Melees since they’re the only ones that can crit), then it is most likely your shield block rate is abysmal against them, you should quickly get more DA from your equipment to fix this.

More Info coming soon. (Such as the modifier to actual tohit which is not used for Shield Block system).

With 1500 DA vs 500 OA, Melee Block chance would go up by 50%. The ‘Actual’ chance to hit appears to be about 45%.
With 500 DA vs 500 OA, there is no change to Melee Block chance, and the ‘Actual’ chance to hit appears to be about 95%.
With 500 DA vs 1500 OA, there is a 50% reduction to Melee Block chance. The ‘Actual’ chance to hit appears to be 145% which allows for a 1.5x Melee Crit.

The following is a chart of Crit bonus vs OA above DA.
500 more OA 1.5x Crit Dmg
400 more OA 1.4x Crit Dmg
300 more OA 1.3x Crit Dmg
200 more OA 1.2x Crit Dmg
100 more OA 1.1x Crit Dmg
99 more OA 1.0x Crit Dmg (essentially, no Crit Dmg, unsure if it would display yellow numbers)

100 Dex Increases your chance to block Projectiles by 10%, this is not an additive it is a modifier. So 30% Block becomes 33% Block. (Evil part If you are an Archer you can not lower your targets chance to Block your arrows)
OA=DA means no chance to Critical, and a 95% chance to hit.
Every 50 DA above attackers OA increases the chance to miss by 2.5% and the chance to block melee attacks by 2.5%. (This part works in reverse, so every 50 DA below your attackers, reduces their chance to miss by 2.5% and your chance to block melee attacks by 2.5%)
You must have atleast 100 OA more than your opponent to be able to critical. Every additional 100 OA above increases your Crit Dmg until you are 500 OA above your opponent.

Check the Complete Guide and Mod List:
Titan Quest Guides, Patches, Mods and Utilities List

Pinhan Pain

Founder of the Kırmızı Perfect. Old-school gamer. Arch Linux fan.

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