Gimme Shelter

about blocking

Chance to Block

A character wearing a shield is able to block physical attacks which already have broken his defense. This ability depends on character class, character level, kind of shield and in dexterity invested status points. Some items as well as Paladin Skill Holy Shield will increase the chance for successful blocking.
The Chance in LoD calculates:

Chance_Block = (Block_Shield + Block_Bonus) * (dex - 15) / (cLvl * 2)

Chance_Block: resulting Blockchance Block_Shield: base block of used shield Block_Bonus: Bonus of items and Holy Shield dex: dexterity cLvl: Character's level

There is a german calculator at d2wissen.

If you want to know how much points in dexterity you need for your maximum blocking chance, use following formula:

dex = 150% * cLvl / ∑Block + 15

dex: needed dexterity cLvl: Charakter's level ∑Block = Block_Shield + Block_Bonus

For Diablo II without expansion ('Classic') dexterity is omitted.

the Shield

Base block rate of used shield differs by class. Paladins are best, 5% inferior are Amazons, Assassins and Barbarians, and again 5% worse are Druid, Necromancer and Sorceress. The block chance displayed on your shield reflects that.

The actual blocking chance is capped at 75%, you won't see it on your shield, but in your character screen while hovering your mouse cursor over displayed defense value.
If your character runs, blocking chance is only a third of that figure. Not sure if the math is done before or after 75% total cap. The Arreat Summit lists as 'after'.
If you hold some item at your cursor with open inventory, your character can't block.

Assassin's Claw Block skill doesn't benefit from increased blocking chance via items. Only skill level counts here.

base blocking of different shields

shield	Name	pal	ama	asn	bar	dru	nec	sor
shield	Name	pal	ama	asn	bar	dru	nec	sor
pal: Paladin; ama: Amazon; asn: Assassin; bar: Barbarian; dru: Druid; nec: Necromancer; sor: Sorceress
	Buckler	30%	25%			20%
	Defender	40%	35%			30%
	Heater	52%	47%			42%
	Small Shield	35%	30%			25%
	Round Shield	42%	37%			32%
	Luna	50%	45%			40%
	Large Shield	42%	37%			32%
	Scutum	44%	39%			34%
	Hyperion	54%	49%			44%
	Kite Shield	38%	33%			28%
	Dragon Shield	48%	43%			38%
	Monarch	52%	47%			42%
	Spike Shield	40%	35%			30%
	Barbed Shield	47%	42%			37%
	Blade Barrier	50%	45%			40%
	Tower Shield	54%	49%			44%
	Pavise
	Aegis
	Bone Shield	50%	45%			40%
	Grim Shield
	Troll Nest
	Gothic Shield	46%	41%			36%
	Ancient Shield
	Ward	54%	49%			44%
paladin specific shields
	Targe	40%
	Akaran Targe
	Sacred Targe	60%
	Rondache	45%
	Akaran Rondache
	Sacred Rondache	58%
	Heraldic Shield	50%
	Protector Shield
	Kurast Shield	55%
	Aerin Shield	52%
	Gilded Shield
	Zakarum Shield
	Crown Shield	55%
	Royal Shield
	Vortex Shield	51%
necromancer specific shields (Totems)
	Preserved Head						23%
	Mummified Trophy
	Minion Skull
	Zombie Head						25%
	Fetish Trophy
	Hellspawn Skull
	Unraveller Head						28%
	Fetish Trophy
	Overseer Skull
	Gargoyle Head						30%
	Cantor Trophy
	Succubus Skull
	Demon Head						33%
	Heirophant Trophy
	Bloodlord Skull

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Faster Block Rate

Blocking itself is an animation of its own. During this animation your character can't do anything else. In patch 1.09 you even could get stuck in 'blocklock', if the chance for block was triggered too often in too short time. A bit of irony, boni to 'Faster Block Rate (FBR)' couldn't prevent this.
Since 1.10 there is noticeably some change in game code referring to animation priorities. The patchlog is clearly foggy about this, but it seems only the first blocking animation is actually displayed, and dependent on FBR for some duration blocking animations are skipped.

But main purpose of FBR is accelerating the actual animation. the amount of single pictures and the duration are class-specific. See german d2wissen for a list of items with FBR bonus.
The Assassin has the ability to block with her claw weapons, if she uses claws in both hands and has evolved her Weapon Block skill. She can block far more foeish attacks than possible while wearing a shield, but she can't do so while moving (both walking and running). The duration of her claw block animation is two frames, this could theoretically benefit from FBR, in practice there is no possibility to achieve this in unmodified game.

Formula

First we'll do the math for effective blocking speed. This is subject to a 'diminishing returns' formula, which means you'll need way larger FBR amounts the better block you want to achieve.

eFBR = [FBR * 120 / (FBR + 120)] + Bonus_skill

eFBR: effective Blockrate FBR: Faster Blockrate via items Bonus_skill: Paladin's Holy Shield skill counts 50 here;
rest equals 0
[ ]: Floor Function (integer)

Werebear with Holy Shield activated

%FBR	fpa
%FBR: Faster Blockrate fpa: Frames per Animation
0	6
8	5
37	4
120	3
2280	2

The necessary figure for animation velocity is commonly 256. There are two exceptions:

• An Amazon wearing a one-handed swinging weapon (all one-handed weapons except daggers and javelins) gets an '88' here.
• A Druid in Werebear shape gets regardless of his equipped weaponry a '200'. This is a general rule for the shape 'Werebear' and not restricted to Druid class. A Paladin in Werebear shape with activated Holy Shield will still get that skill's extra bonus to block, but duration of blocking animation will decrease noticeably due to the other shape.

Also we need a class-specific constant Block_base.
Attention: this is not the number of frames needed for blocking without FBR!

Class	Blockbase
Amazon	3
Assassin	3
Barbarian	4
Druide Werebear	5
Druide Werewolf	5
Druide Human	6
Necromancer	6
Paladin	3
Sorceress	5

So we throw this all in one term and get:

Block_f = { 256 * Block_base / ([v_anim * (50 + eFBR) / 100])} - 1

Block_f: Blocking Speed in Frames Block_base: class-specific constant base Block v_anim: Animation Velocity eFBR: effective Blocking Speed of above formula [ ]: Floor Function { }: Ceiling Function

also see:

• table of Blocking Speeds
• about GetHit animations by Rivo aka Karon
• Missile Blocking by Nefarius at the Keep

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Blocking while shape shifted

A player unit can transform into Werewolf, Werebear, Vampire or Undead Fetish. Vampire and Fetish shaped players will use Get Hit animation instead of Blocking Animation (those shapes lack blocking animations). Actually Faster Hit Recovery will accelerate blocking speed then.

see also:

• Warning about Trang Oul's and Blocking
• transformed characters in Phrozen Keep

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non-player units

Buried in the game's configuration files are individual blocking chances for every unit, separated in Normal/Nightmare/Hell difficulties.
But to make use of this any unit needs a shield and a special blocking animation. An Iron Wolf hireling wears a shield, but lacks blocking animation, so he can't block.
But some units are able to block without a shield and without an assigned animation. This is controlled by NoShldBlock column in monstats.txt.
This applies to all Greater Mummies, all Oblivion Knights and all Act Bosses including their several clones. It is especially not activated for any Golem, the Valkyrie, both Assassin Shadows and other Pets.

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Credits

• Karon aka Rivo
• Nefarius
• nookiestar
• tommi
• RTB
• Ruvanal

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Contact me via E-Mail, if you like.

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