Chance to Block Mechanics
Last Updated:March 6, 2024|Changelog
Chance to Block is a mechanic that has defensive and offensive implications. Negating all damage of an attack that has been blocked, it is a significant boost for your survivability when used as an additional layer of defense. To use it as such, you have to sacrifice maximum Life. However, it becomes incredibly important for Characters engaged in front line fights, and for Hardcore in general.
Monsters also benefit from Chance to Block.
Mechanics
- While wearing a Shield, a Character has a % Chance to Block. This can be seen by hovering over the Defense value on your Character Screen. Chance to Block is capped at 75% while using Skills without movement, standing, walking or using Whirlwind.
- When running, the % Chance to Block is reduced to 1/3, reducing the cap to 25%.
- A successful block negates the damage from the incoming attack.
- The total % Chance to Block is determined using the Character Level (clvl), a Character specific bonus, the base % Chance to Block on the Shield, sources of "x% Increased Chance of Blocking", and the total Dexterity value.
- The % Chance to Block is applied after an attack successfully passes the hit check but before the Amazon's Dodge, Avoid, and Evade.
- Successful blocks trigger an animation. The duration of this animation is determined by the Block Rate Breakpoint, which is influenced by the Affix "+x% Faster Block Rate".
- You can block immediately after the animation of a previous block is over. This can cause you to get into a "Block-Lock".
What can be blocked?
While most attacks can be blocked, there are a number of exceptions. There are also some unintuitive sources of incoming damage that can be blocked. Check out the following table:
| Can be blocked | Can't be blocked |
| Melee Attacks | Level 49+ Fire Arrow and Cold Arrow |
| Fired Arrows and Bolts | Lightning Bolt |
| Javelins, Throwing Axes, and Throwing Knives | Explosion of Molten Boulder Check out the Skill mechanics here. |
| Missiles with Physical Damage component | The radial damage of Tornado Check out the Skill mechanics here. |
| Death explosions from Bone Fetishes and Suicide Minions | Radial impact damage of Armageddon Check out the Skill mechanics here. |
| Explosions from Fire Enchanted Elites | Corpse Explosion |
| Smite | |
| Charge from Claw Vipers and Reanimated Hordes |
Calculations
Dexterity required for 75% Chance to Block
The most frequent question in regard to Chance to Block is: "How much Dexterity do I need to reach 75%"? To calculate this, we need the following 3 variables:
- Shield = Base Chance to Block of the used Shield, including the Character's bonus
- Bonus = Sum of all "x% Increased Chance of Blocking" values and Holy Shield when active
- clvl = Character Level
Formula
Dexterity = 15 + ceil(150 * clvl / (Shield + Bonus))
Example:
Let's put this formula to practice using the Character shown on the right. Our Paladin has 50 Dexterity at Level 73 and has a Skill Level 10 Holy Shield active.
Shield = 52% (see table below!)
Bonus = 37% + 10% + 25% + 30% = 102%
clvl = 73
Dexterity = 15 + ceil(150 * 73 / (52 + 102))
Dexterity = 15 + ceil(150 * 73 / 154)
Dexterity = 15 + ceil(71.1...)
Dexterity = 15 + 72 = 87
Current % Chance to Block
To calculate the current % Chance to Block, we need the following 4 variables:
- Shield = Base Chance to Block of the used Shield, including the Character bonus
- Bonus = Sum of all "x% Increased Chance of Blocking" values and Holy Shield when active
- Dexterity = Total value of Dexterity (Character Screen)
- clvl = Character Level
Formula
CTB = min(floor((Shield + Bonus) * (Dexterity - 15) / (clvl * 2)), 75) %
Example
Let's put this formula to practice using the Character shown on the right. Our Paladin has 50 Dexterity at Level 73 and has a Skill Level 10 Holy Shield active.
Shield = 52% (see table below!)
Bonus = 37% + 10% + 25% + 30% = 102%
Dexterity = 50
clvl = 73
CTB = min(floor((52 + 102) * (50 - 15) / (73 * 2)), 75) %
CTB = min((floor(154 * 35 / 146)), 75) %
CTB = min(floor(36.9..),75) %
CTB = 36 %
Base Chance to Block
Every Shield in Diablo 2 has a base % Chance to Block, shown in the tooltip. This % is the sum of the Shield's base value and a bonus value, which depends on the Character that looks at the Shield.
Character Bonuses
Shield Values
Adding these values to the Shield bases lead to the following % Chance to Block values displayed in the game, including the Character bonus. If you hover over the Shield name on the left, you can see the base value without the Character bonus, in the following accordions:
Only a Paladin can equip Auric Shields, however, when other Characters look at an Auric Shield, their tooltip shows the % Chance to Block using their Character's bonus.
Normal
| Shield Base | Chance to Block |
| Targe | 40% |
| Rondache | 45% |
| Heraldic Shield | 50% |
| Aerin Shield | 52% |
| Crown Shield | 55% |
Exceptional
| Shield Base | Chance to Block |
| Akaran Targe | 40% |
| Akaran Rondache | 45% |
| Protector Shield | 50% |
| Gilded Shield | 52% |
| Royal Shield | 55% |
Elite
| Shield Base | Chance to Block |
| Sacred Targe | 60% |
| Sacred Rondache | 58% |
| Kurast Shield | 55% |
| Zakarum Shield | 52% |
| Vortex Shield | 49% |
Only a Necromancer can equip Voodoo Shields, however, when other Characters look at a Voodoo Shield, their tooltip shows the % Chance to Block using the Character's bonus.
Normal
| Shield Base | Chance to Block |
| Preserved Head | 23% |
| Zombie Head | 25% |
| Unravaler Head | 28% |
| Gargoyle Head | 30% |
| Demon Head | 32% |
Exceptional
| Shield Base | Chance to Block |
| Mummified Trophy | 23% |
| Fetish Trophy | 25% |
| Sexton Trophy | 28% |
| Cantor Trophy | 30% |
| Hierophant Trophy | 32% |
Elite
| Shield Base | Chance to Block |
| Minion Skull | 23% |
| Hellspawn Skull | 25% |
| Overseer Skull | 28% |
| Succubus Skull | 30% |
| Bloodlord Skull | 32% |
Increased Chance of Blocking
In the calculation for the total % Chance to Block, the summed up % value of this Affix, across all item slots, is added to the base % Chance to Block of the Shield. If this Affix is on the Shield, it shows in the tooltip of the Shield. It doesn't add to the tooltip, if it comes from other item slots.
Sources
1)The tooltip, when hovered over, shows the % Chance to Block, using a Barbarian.
Regular Shields
| Shields | Increased Chance of Blocking | |
| Magic Shield of Blocking1 Rare Shield1 | 10% | |
| Magic Shield of Deflecting1 Rare Shield1 | 20% | |
| Caster Crafted Shield | 5-10% | |
| Hit Power Crafted Shield | 5-10% | |
| Rhyme | 20% | |
| Sanctuary | 20% | |
| Sigon's Guard | 20% | |
| Civerb's Ward | 15% | |
| Whitstan's Guard | 55% | |
| Taebaek's Glory | 25% | |
| Pelta Lunata | 20% | |
| Umbral Disk | 30% | |
| Stormguild | 30% | |
| Swordback Hold | 20% | |
| Steelclash | 25% | |
| Bverrit Keep | 10% | |
| The Ward | 10% | |
| Visceratuant | 30% | |
| Moser's Blessed Circle | 25% | |
| Stormchaser | 20% | |
| Gerke's Sanctuary | 30% | |
| Radament's Sphere | 20% | |
| Spirit Ward | 20-30% | |
| Stormshield | 25% | |
Auric Shields
| Auric Shields | Increased Chance of Blocking | |
| Herald of Zakarum | 30% | |
| Griswold's Honor | 20% | |
| Alma Negra | 20% | |
Voodoo Heads
| Voodoo Heads: | Increased Chance of Blocking | |
| Homunculus | 40% | |
| Trang-Oul's Wing | 30% | |
| Source | Increased Chance of Blocking | |
| Eld Rune socketed in a Shield | 7% | |
| Safety Crafted Amulets | 1-10% | |
| Full Isenhart's Armory Set bonus | 30% | |
| Twitchthroe | 25% | |
| Guardian Angel | 20% | |
| Swordguard | 20% | |
Block Rate
Blocking is an animation that is performed when you successfully block a physical attack. This includes the Assassins' Weapon Block. Your Block Rate determines how fast this animation is performed.
Mechanics
- While blocking, you are unable to perform any actions.
- You can block consecutive attacks, as soon as your animation finishes, potentially leading to a full "block lock".
- You can speed up the animation by using gear with +xx% Faster Block Rate (FBR).
- This Affix is exclusive to Shields, making it very hard to come by. The only exceptions to this rule are Guardian Angel and Pattern.
Note for the calculations:
- ceil = round up the term that follows
- floor = round down the term that follows
Before we can use the formulas for Block Rate, we need the following values:
- The total +xx% Faster Block Rate from our gear.
- The "Block Base" of the Character. Check in the table below.
- The "Animation Speed" of the Character. Check in the table below.
With these values, we can go through the following formulas.
Effective Faster Block Rate (EFBR):
EFBR = floor(FBR * 120 / (FBR + 120))
With Holy Shield
EFBR = floor(FBR * 120 / (FBR + 120)) + 50
Block Frames
Block Frames = ceil(256 * Block Base / floor(Animation Speed * (50 + EFBR) / 100) - 1)
| Character | Block Base | Animation Speed |
| Amazon | 3 | 256 |
| Amazon (1-handed Weapons) (*) | 3 | 88 |
| Assassin | 3 | 256 |
| Barbarian | 4 | 256 |
| Druid | 6 | 256 |
| Werewolf | 5 | 256 |
| Werebear | 5 | 200 |
| Necromancer | 6 | 256 |
| Paladin | 3 | 256 |
| Sorceress | 5 | 256 |
(*) This only means: 1-handed Axes, Clubs, Maces, Hammers, Scepters, Swords, Throwing Axes.
Practical example with 50 FBR on a Paladin without Holy Shield:
Effective Faster Block Rate (EFBR)
EFBR = floor(6,000 / 170)
EFBR = floor(35.294...)
EFBR = 35
Block Frames
Block Frames = ceil(768 / floor(256 * 85 / 100) -1)
Block Frames = ceil(768 / 217 - 1)
Block Frames = ceil(2.539...)
Block Frames = 3
This means the Paladin with 50 FBR and without Holy Shield uses 3 Frames for the Block animation.
Practical example with 50 FHR on a Paladin with Holy Shield:
Effective Faster Block Rate (EFBR)
EFBR = floor(6,000 / 170) + 50
EFBR = floor(35.294...) + 50
EFBR = 85
Block Frames
Block Frames = ceil(768 / 345 - 1)
Block Frames = ceil(1.226...)
Block Frames = 2
This means the Paladin with 50 FBR and with Holy Shield uses 2 Frames for the Block animation.
Breakpoints
+140% Faster Block Rate (155% on Paladin) is the maximum you can achieve. The tables below show the Breakpoints with achievable Faster Block Rate values.
1-Handed Swinging Weapons (Axes, Clubs, Maces, Scepters, Swords, Throwing Axes, and Wands):
| Faster Block Rate | 0 | 4 | 6 | 11 | 15 | 23 | 29 | 40 | 56 | 80 | 120 |
| Block Frames | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 |
Other Weapons:
| Faster Block Rate | 0 | 13 | 32 | 86 |
| Block Frames | 5 | 4 | 3 | 2 |
| Faster Block Rate | 0 | 13 | 32 | 86 |
| Block Frames | 5 | 4 | 3 | 2 |
| Faster Block Rate | 0 | 9 | 20 | 42 | 86 |
| Block Frames | 7 | 6 | 5 | 4 | 3 |
Human form:
| Faster Block Rate | 0 | 6 | 13 | 20 | 32 | 52 | 86 |
| Block Frames | 11 | 10 | 9 | 8 | 7 | 6 | 5 |
Werewolf:
| Faster Block Rate | 0 | 7 | 15 | 27 | 48 | 86 |
| Block Frames | 9 | 8 | 7 | 6 | 5 | 4 |
Werebear:
| Faster Block Rate | 0 | 5 | 10 | 16 | 27 | 40 | 65 | 109 |
| Block Frames | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 |
| Faster Block Rate | 0 | 6 | 13 | 20 | 32 | 52 | 86 |
| Block Frames | 11 | 10 | 9 | 8 | 7 | 6 | 5 |
Without Holy Shield:
| Faster Block Rate | 0 | 13 | 32 | 86 |
| Block Frames | 5 | 4 | 3 | 2 |
With Holy Shield:
| Faster Block Rate | 0 | 86 |
| Block Frames | 2 | 1 |
| Faster Block Rate | 0 | 7 | 15 | 27 | 48 | 86 |
| Block Frames | 9 | 8 | 7 | 6 | 5 | 4 |
Mercenaries and Pets
- No Mercenary can block attacks. The % Chance to Block from a Shield equipped on the Iron Wolf (Act 3 Mercenary) does not apply.
- Among all the Pet type minions, only the Necroskeleton (Raise Skeleton) has a 3% Chance to Block when using a Shield.
Note: The visual model wearing a Shield is actually not an indicator whether it has a Chance to Block. - The % Chance to Block from a Shield used to summon an Iron Golem is not applied to the Golem.
Monsters with Chance to Block
Hidden in the game files, monsters receive a % Chance to Block for each difficulty. They only execute that Chance to Block if they either spawn with a Shield and have a blocking animation enabled, or if they are tagged with "NoShldBlock" in the monstats.txt. Check out the tables below, showing what monsters have a Chance to Block with or without Shields.
- Monsters with no value in the Normal column don't spawn in normal. They are guest monsters throughout Act 5 in Nightmare and Hell difficulty.
- Monsters with no value in Normal and Nightmare don't spawn in these difficulties. They are guest monsters in the Pandemonium Event (see Ubers article) in Hell.
| Monster | Normal | Nightmare | Hell |
| Dark Hunter | 12% | 12% | 12% |
| Vile Hunter | 18% | 18% | 18% |
| Dark Stalker | 25% | 25% | 25% |
| Black Rogue | 33% | 33% | 33% |
| Flesh Hunter | 40% | 40% | 40% |
| Flesh Hunter | - | - | 40% |
| Fallen | 9% | 9% | 9% |
| Carver | 16% | 16% | 16% |
| Devilkin | 25% | 25% | 25% |
| Dark One | 36% | 36% | 36% |
| Warped One | 49% | 49% | 49% |
| Carver | - | 49% | 49% |
| Devilkin | - | 49% | 49% |
| Dark One | - | 49% | 49% |
| Huntress | 15% | 15% | 15% |
| Sabre Cat | 20% | 20% | 20% |
| Night Tiger | 25% | 25% | 25% |
| Hell Cat | 30% | 30% | 30% |
| Sabre Cat | - | 15% | 15% |
| Skeleton | 10% | 10% | 10% |
| Returned | 15% | 15% | 15% |
| Bone Warrior | 20% | 20% | 20% |
| Burning Dead | 25% | 25% | 25% |
| Horror | 30% | 30% | 30% |
| Bone Warrior | - | 30% | 30% |
| Returned | - | 30% | 30% |
| Returned | - | - | 30% |
| Slinger | 15% | 15% | 15% |
| Spear Cat | 16% | 16% | 16% |
| Hell Slinger | 19% | 19% | 19% |
| Spear Cat | 16% | 16% | 16% |
| Night Slinger | 17% | 17% | 17% |
| Slinger | - | 19% | 19% |
| Slinger | - | 19% | 19% |
| Slinger | - | 19% | 19% |
| Monster | Normal | Nightmare | Hell |
| Doom Knight1 | 24% | 24% | 24% |
| Hollow One2 | 0% | 15% | 33% |
| Guardian2 | 0% | 15% | 33% |
| Unraveler2 | 0% | 15% | 33% |
| Horadrim Ancient2 | 0% | 15% | 33% |
| Unraveler2 | 0% | 15% | 33% |
| Andariel | 0% | 20% | 40% |
| Duriel | 0% | 25% | 50% |
| Mephisto | 20% | 40% | 50% |
| Diablo | 25% | 40% | 50% |
| Baal | 40% | 45% | 55% |
| Baal (clone) | 40% | 45% | 55% |
| Diablo clone | - | - | 50% |
| Lilith | - | - | 40% |
| Uber Duriel | - | - | 50% |
| Uber Mephisto | - | - | 50% |
| Uber Diablo | - | - | 50% |
| Uber Baal | - | - | 55% |
- Applies to Doom Knights in Act 4 only. Doom Knights in Act 5 cannot block.
- Applies to those spawning in Act 2 and Act 3, as well as Achmel the Cursed and his Minions in Act 5. Other monsters of this type spawned in Act 5 cannot block.
Summary
- Chance to Block is a very good way to mitigate damage taken from attacks.
- Chance to Block is more dangerous in the early game, than the benefits of Blocking because you have to sacrifice Vitality. Once you have a good Shield, consider speccing into Chance to Block.
- Hardcore players should consider going for 75% (max) Chance to Block with almost every build.
- The Block Animation speed is improved by +x% Faster Block Rate.
- You can get "Block-Locked", meaning you block multiple times in a row and you are not able to take any other actions.
- Some monsters have a Chance to Block, even if they don’t show the animation.
Phew... This post was longer than expected. As this is a very important mechanic, it is well worth the read. Make yourself familiar with all Chance to Block nuances!
Credits
Written by Teo1904
Reviewed by MacroBioBoi