Repost of my old guide, "Blocking Explained"
Removed the introductory section, included a table of contents, and corrected a few errors. Preserved most of the original setup.

Table of Contents
- [1] Facts about Blocking
- [2] The Blocking Formula
- [3] Digesting the Formula
- [4] Calculating Total Blocking
- [5] Holy Shield and Weapon Block "Breakpoints"
- [6] How Much Dexterity for Max Block ?
- [7] Additional Links


[1] Facts about Blocking

(Read these to avoid misconceptions)

• Only assassins can block without a shield (Weapon Block) > http://www.battle.net/diablo2exp/skills/assassin-shadow.shtml#weaponblock
• Blocking bonuses from other items apply only if you are already wielding a shield. They do NOT work with Weapon Block.
• The Chance to Block displayed on your shield is the shield block percentage (including bonus from Holy Shield if applied).
• Shield block may exceed 75 %. 'Chance to Block: 75%' is merely the highest number that can display on your shield.
• The +7% blocking bonus from an Eld Rune when socketed into a shield is added to the shield block.
• Shield block is class-specific.
• Amazons, assassins, and barbarians have 5 % less shield block than paladins.
• Necromancers, sorceresses, and druids have 10 % less shield block than paladins.
• Total Blocking will show if you hover the cursor above the field labelled 'Defense' in the character screen.
• Total Blocking is capped at 75 % (25 % when running with a shield).

[2] The Blocking Formula

Your total blocking ( T ) is calculated from blocking bonuses from multiple sources ( B ), your dexterity ( D ), and your current character level ( C ). The blocking formula
(which can be found at the Arreat Summit as well) reads,

• T = [B*(D - 15) / (2*C)]

(capped at 75 %). The final calculation step uses integers, indicated by the brackets [ ]. Any decimals are truncated, e.g. [47.6] % = 47 %.

T: Total Blocking
This is the true blocking as displayed on the character screen when mousing the 'Defense' field. Your total blocking will only show if you are currently wielding a shield
or if you are dual-wielding claws (WB). Otherwise your blocking is 0.

Assassins using Weapon Block have a total blocking equal to the WB %. The blocking formula does NOT apply to claw-claw block.

B: Blocking from multiple sources

• Shield (shield block)
• Certain pieces of unique body armor (Twitchthroe, Guardian Angel)
• Crafted Safety Amulet > http://www.battle.net/diablo2exp/items/crafted/safety.shtml
• Holy Shield (paladin only)

Each of these stack. The resulting blocking sum is assigned to the item Blocking variable ( B ) used in the blocking formula.

Note
Again, B is NOT capped. Only T is capped at 75 %.

D: Dexterity
Your total dexterity, including bonuses from charms and/or equipment.

C: Character level
Self-explanatory.


[3] Digesting the Formula

Before we continue, let's dwell a little on the blocking formula. What is the significance of it ? Well, it's a linear relation with respect to both B and D, but an inverse relation
with respect to C. Meaning that character level plays a rather huge role to your blocking at lower levels which you might have experienced unless you spent enough points
on dexterity. As you approach higher levels, the impact of C on total blocking ( T ) diminishes somewhat. B and D are of major importance in both cases.

B is the main factor because of the way the game applies blocking bonuses, as well as the magnitude of these on items or from the Holy Shield skill. Picking the right shield
in terms of blocking potential is (not surprisingly) crucial to your total blocking. Obviously, paladins have a considerable advantage due to HS.

In view of this, people wanting to optimize their ability to block will want to know how much dexterity they need to obtain max block (75 %) at a given level.


[4] Calculating Total Blocking

Let's look at 3 entirely different setups.

#1: Level 80 sorceress (D = 75, Spirit Monarch, no other items adding to B )
Monarch: shield block = 42 % (sorc), thus B = 42 %.

T = [42 * (75 - 15) / (2*80)] % = 15 %

#2: Level 85 assassin (D = 100, claw-claw, WB lvl 10)
WB lvl 10: CtB = 50 %

T = 50 %

Dexterity and character level as well as any item adding to B are completely irrelevant in this case. Keep in mind, unlike a shield, WB does not work while walking or running.

#3: Level 90 Paladin (D = 114, HoZ, Guardian Angel, HS lvl 20)
HoZ (Gilded Shield): shield block = (52 + 30) % = 82 % (pala)
Guardian Angel: +20% ICB
HS lvl 20: +35% ICB

T = [(82 + 20 + 35) * (114 - 15) / (2*90)] % = 75 %

As you can easily check for yourself, 114 dex is the minimum required to obtain max block with this setup at lvl 90. The result remains unchanged if you upgrade HoZ, as the
new base shield (Zakarum Shield) carries the same base shield block (52%) as a Gilded Shield.


[5] Holy Shield and Weapon Block "Breakpoints"

Successful Blocking +X% and corresponding levels of HS (1-20) from the AS,
> http://www.battle.net/diablo2exp/skills/paladin-combat.shtml#holyshield

HS Blocking "Breakpoints" above lvl 20 (+35 %)
lvl 23 (+36 %)
lvl 27 (+37 %)
lvl 36 (+38 %)
lvl 45 (+39 %)
lvl 60 (+40 %)

WB "Breakpoints" above lvl 20 (57 %)
lvl 21 (58 %)
lvl 23 (59 %)
lvl 26 (60 %)
lvl 31 (61 %)
lvl 36 (62 %)
lvl 42 (63 %)
lvl 49 (64 %)
lvl 60 (65 %)

Source: Chippydip's Skill Planner page, quoted @ Battle.net Forums > http://www.battle.net/forums/thread.aspx?fn=d2-general&t=1310762&p=1&#post1310762 (post #2)


[6] How Much Dexterity for Max Block ?

For optimization purposes you must previously decide what equipment to use and what character level you are aiming for. There are several ways to determine the amount
of dexterity needed for max block. Choose whichever you prefer.

• a ) Browse the 'Defense' field in the character screen and keep adding dexterity until the chance to block reads 75 %. Repeat this step whenever you gain a level.
• b ) Use the blocking formula, toss in some values of D and adjust these accordingly. Terminate iterating when 1 dexterity point less would only just imply T < 75 %.
• c ) Use a blocking calculator. Peter Paul Ruben's calculator seems to be quite handy > http://www.baronsbazaar.invisionzone.com/ppr/block_calc.html
• d ) Invert the blocking formula, expressing D in terms of B and C to obtain T = 75 %. Remembering the round-off procedure, we proceed as follows,

• D = ] 75 * (2*C) / B + 15 [

where ] [ tells us to 'round up', e.g. ]336.43[ = 337. This ensures that we have the minimum dexterity needed for max block, according to the blocking formula.

At this stage, you may wish to repeat example #3, using the inverted formula above, just to convince yourself that you get the desired amount of dexterity (114).


[7] Additional Links

Faster Block Rate (FBR) breakpoints (Paladin selected - you may change the character class accordingly in the link)
> http://www.pvpwest.com/Paladin.php

Shield Attributes (from the Arreat Summit)
> http://www.battle.net/diablo2exp/items/normal/shields.shtml
> http://www.battle.net/diablo2exp/items/normal/paladinshields.shtml

Nice layout and all, I got just one question for you.

Why did you do this? Didn't read a thing.
Blocking is quite simple, stat dex untill you reach 75%.

This looks much better than "Blocking Explained".
Table of contents helps and leaving burlywood color away wasn't bad idea.

This post was edited by RaBBit3x on Aug 27 2008 09:00am

Was talking to a guy ingame yday about some blocking formulas, didnt even think of checking here untill now - and here we are =) Nice one, well written and nicely edited

voting for Sticky

This post was edited by Aveign on Aug 27 2008 09:00am

Vouch.


you nerd, good job.

wow very usefull
ty

There is more to blocking than just adding dexterity. Well, if you would take your time to read the guide, that is.


Absolutely. I got sick of that colour and the obvious introduction in the old guide.

Thanks for the heads up, folks. Hopefully, the new guide will come in handy.

This post was edited by Faelwen on Aug 27 2008 09:35am

I would like to help you add a section on how block changed from 1.09 to 1.10 with the addition of block timers and their effect on real-time blocking. I wrote a mini-guide on this in the past, and I think it is critical information for many people, especially those who duel vs melee without uninterruptable attacks.

This post was edited by inkanddagger on Aug 27 2008 03:58pm

I`d mention the other nice breakpoints for hs

16 an 19 as well because for some builds or with some skillplans you don´t wanna go for 20 hs or higher f.,e. certain hammerdin or avenger setups

Maybe clarify that stacking shield block over 75% makes it easier to acheive max block.