As promised, we bring you the first Diablo 3 exploit found.

This exploit basically lets you get two attacks in the time it takes to do one. While this may not seem like much off hand, think of it this way, you can get double damage in the same time span. It also bypasses weapon delays, etc. It really is a very nice exploit.

To summarize here is how it works. You put one skill on your left mouse button, and a second skill on your hotbar (ie key 1). You press the mouse button, and then immediately press the hotkey 1. Since the hotkey  will take priority over the mouse, it will cause the attack animation to stop and start the hotkey attack.

Full length explanation follows as well as a video showing off the D3 exploit on different classes.

In diablo 3 (d3) the keyboard takes priority over the mouse. This allows an interruption in the normal game processing routines. In this particular case, animation cancelling. Using this technique, does have some caveats.

1) Animations are canceled allowing the character to spam spells drastically increased rate.
2) Spells like electrocute can be cast 2x
3) Channeled spells if cancelled will lock your character until your mana (hate, etc) is gone.

Legend
LMB = Left Mouse Button
RMB = Right Mouse Button
Mouse Button = Either LMB or RMB
Hotkey = Skills bound to the hotkey bar, but not in either LMB or RMB.  Default keys are 1-6.

Animation Cancelling Rules
1) Attacks bound to a mouse button may be cancelled for an attack bound to a hotkey.
2) You cannot cancel a spell/attack with the same spell/attack.
3) Channeled spells are fubar atm, because if cancelled, it will still drain your mana pool until its gone.
4) You cannot use auto-attack to cancel because it can only appear on a mouse button.
5) Hotkey attacks cannot be on the mouse buttons or they will not work.

How To perform the Diablo 3 Exploit
1) Bind an attack to your Left Mouse Button.  (Ex: Cleave)
2) Bind another attack to a Hotkey (Ex. Bash @ Keyboard key:1).  Just be sure that the hotkey attack is not on the right mouse button (see rules above)
3) Attack with Cleave
4) After Cleave’s damage has been dealt, press the hotkey for the 2nd attack.

So, what does all of this mean?
When you cancel the attack animation, you stop the recovery time. This causes the next attack to perform instantly . Thus you are attacking faster then you should be able too.

In Diablo 3, the basic spell routine will follow these steps:
1) Before – The spell/attack has been started but it has not damaged the mob yet.
2) During – Damage is being delt.
3) After – Damage has been delt, and the player is back in the normal state.  The player cannot perform any actions during this time.  This begins just after the damage has been delt, until the player can attack again.
4) Cooldown (optional) – This is the period in which the player must wait before he can cast the spell again.

Diablo 3’s spells and attacks conform to these steps.  Using the Barbarian’s Cleave as an example:
1) Before – The Barbarian draws his weapon back.
2) During – The swing takes place, and you see the red swipe effect.
3) After – The barbarian returns to his normal stance (not attacking)
4) Cooldown – Not all attacks and spells have cooldowns, in this case, the cooldown is added to the attack routine so it is not an instant effect but takes place over time.

By cancelling an attack, you skip step 3.

Lets take a closer look. Normally the Barbarian can do 1 cleave every second, or one bash every second. So in 10 seconds, he can get 5 cleaves and 5 bashes. However with the diablo 3 exploit for cancelling he can get 10 attack in 7.5 seconds!!!

Lets map the time it takes to do 5 Cleaves and 5 Bashes the normal way:
0.0 Seconds: Cleave(1)
1.0 Seconds: Bash(1)
2.0 Seconds: Cleave(2)
3.0 Seconds: Bash(2)
4.0 Seconds: Cleave(3)
5.0 Seconds: Bash(3)
6.0 Seconds: Cleave(4)
7.0 Seconds: Bash(4)
8.0 Seconds: Cleave(5)
9.0 Seconds: Bash(5)
10.0 Seconds: DONE – 10 Attacks in 10 Seconds

Now with cancelling:
0.0 Seconds: Cleave(1)
0.5 Seconds: Bash(1)
1.5 Seconds: Cleave(2)
2.0 Seconds: Bash(2)
3.0 Seconds: Cleave(3)
3.5 Seconds: Bash(3)
4.5 Seconds: Cleave(4)
5.0 Seconds: Bash(4)
6.0 Seconds: Cleave(5)
6.5 Seconds: Bash(5)
7.5 Seconds: DONE – 10 Attacks in 7.5 Seconds

Video Notes: