I discovered this by accident while cancelling the animation of the Witch Doctor's Firebomb attack. We have a bug report already submitted to Blizzard just in case this isn't supposed to be in the game.
Aside from some bugs that lock up your character state, all signs point to this being a feature. If not, we need to make sure this stays, because this type of thing can really raise the skill ceiling for this game (and it sorely needs it with how easy it's shaping up to be). This is your clarion call TL. Stuff is about to get awesome after the vid. Do your part and make sure this stays in the game!
+ Show Spoiler +
Video Notes:
00m00s - Show basic repeating Cleave
00m07s - Show basic repeating Frenzy
00m14s - Cancel Cleave into Frenzy
00m26s - Cancelling 2nd attack of Crippling Wave 3rd attack of Fists of Thunder
00m38s - Cancel Autoattack into 1st attack of Fists of Thunder
00m50s - Show basic repeating Dashing Strike speed
00m58s - Show Dashing Strike cancelled into Fists of Thunder repeat
01m08s - 1st Attack of Deadly Reach cancelled into 2nd attack of Fists of Thunder, followed by 3rd attack of Deadly Reach
01m14s - Cancel Spectral Blade into Electrocute. Also shows bug where you can get double-electrocute sometimes.
01m39s - Cancel Spectral Blade into Shock Pulse.
01m48s - Cancel Spectral Blade into Magic Missile.
01m57s - Cancel Spectral Blade into Energy Twister
02m05s- Show Basic Hungering Arrow & Auto Attack
02m12s - Cancel Auto Attack into Evasive Fire.
02m35s - Cancel Grenades into Hungering Arrow. Also cancel auto attack into Hungering Arrow
02m56s - Showcase various bugs that happen when trying to cancel some moves
1) Animations can be canceled giving the ability to cast at a greatly increased rate.
2) Electrocute (And possibly other spells) will cast twice instead of once
3) Canceling out of channeled spells will lock your character until your mana/hate/etc.. is depleted. (This is the only buggy part)
Link to B.net bug report: http://us.battle.net/d3/en/forum/topic/3279043269
Even if this is a bug, we need to tell Blizzard that stuff like this is awesome and should stay in the game! Put some feedback on the post! Note - RobotGilardi is my brother. I did not steal the bug report and post it here, I wrote it for him and he posted it on b.net :D
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 LMB or RMB may be cancelled into attacks bound on a Hotkey.
2) You may not cancel with an attack found bound to either Mouse Button.
3) A cancellable attack may appear on both a Mouse Button and a Hotkey. However, this does not allow it to cancel other moves since it violates rule #2.
4) Channeled spells may not cancel into or out of properly without messing up the character state
5) The same attack cannot cancel into itself, as this would require violating rule #2.
6) Autoattacks can never be the canceller since they can only appear on a Mouse Button.
How To
1) Bind an attack to LMB. (Ex: Cleave)
2) Bind another, different attack to a Hotkey (Ex. Bash @ Keyboard key:1). Make sure this second attack does not appear on a Mouse Button. (Rule #2)
3) Attack with Cleave
4) After Cleave’s damage has been dealt, press the hotkey for the 2nd attack.
What does this mean to me?
Cancelling moves can negate recovery time, and improve damage dealt by attacking more often.
To understand how this can work in your favor, you need to understand how attacks work.
In fighting games, an attack has 4 phases:
1) Startup - Attack animation has started, but no damage has been dealt yet.
2) Active - Attack is active and dealing damage. This phase begins when the first frame at which the attack’s hitboxes become active.
3) Recovery - Attack damage has completed and the character is animating back to a neutral state. The character is unable to perform actions during this phase. This phase begins at the first frame in which the attack stops dealing damage, and lasts until the character is able to perform another action.
4) Cooldown (optional) - This is the refractory period in which the character cannot perform the attack again. In Diablo 3, only some moves have cooldowns.
Diablo 3’s attacks conform to these phases. Using the Barbarian’s Cleave as an example:
1) Startup - The Barbarian rears his weapon back.
2) Active - The red swipe effect of the weapon cleaving appears, and the attack deals damage
3) Recovery - The Barbarian animates back to neutral.
4) Cooldown - There is no cooldown on this move. It is based on weapon speed, which factors into speed of the first 3 states.
By cancelling an attack, you skip its Recovery state.
If you cancel an attack on the same frame that the Attack phase begins, then the cancelled attack will still do all of its damage. The cancelled attack will also play out all of its entire Attack phase even as you transition into phases of a different attack.
Therefore: To maximize damage. Cancel moves with long recovery, but quick startup into fast moves
Clarification: You do NOT need to perform this on the exact frame. This is not a "Just Frame" as it would be called in the fight game world. Most cancellable attacks may be cancelled at any time. cancelling after or during the first Active frame will allow both attacks to deal damage.
“Hey! That’s not a DPS increase! I can tell because I’m a scientist!”
Nope. It’s a substantial increase that improves the slower your weapon is. Lets use this example:
Given:
Cleave and Bash both take 1 second to complete, meaning you can attack once every second.
You’re cancelling Cleave into Bash.
Cleave’s Active phase starts at 0.5 seconds into the attack and that you’re able to consistently cancel at that point.
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
Applications
Some characters have better applications than others. I hope that runes change up the animations of certain moves to offer better possibilities. Right now the Barbarian and Monk can make the most use out of the trick.
Barbarian
Cleave cancelled into Frenzy with Dual Wield: If you have fast weapons, your Frenzy comes out and finishes VERY fast, so you can essentially enjoy Frenzy stacks for free.
Any Rage Generator cancelled into Hammer of the Ancients or Weapon Throw: Classic 2for1 application.
Demon Hunter
Autoattack Cancelled into a Rage Spender: With the "Fundamentals" Passive, your hatred can regenerate as you use your abilities.
Vault into Anything: You can cancel vault mid-animation. Sometimes it screws up and teleports you to the final destination. Sometimes it cuts it short. Useful for a quick PVP dodge probably.
Grenades into Anything. Grenades have a long Recovery Phase. Skip it.
Monk
All Spirit Generators into other spirit generators. Best application is Crippling Wave on a Mouse Button since it has the slowest Recovery phase and benefits the most from being cancelled.
Exploding Palm is a great canceller because of its speed.
Dashing Strike into Autoattack or Exploding Palm to cancel the recovery after teleport.
Lashing Tail Kick - Cancel the recovery.
Witch Doctor
He doesn't have many uses since most of his attacks don't come out quick enough to really justify spamming weaveable attacks. I've only found 2 good applications.
Zombie Charger cancelled into Poison Frogs or vice versa.
Haunt cancelled into anything- This is actually pretty good. Haunt emits almost immediately as the Startup phase is very short. Most of Haunt's casting time is on the Recovery Phase. Best I've found is Haunt into Firebomb or Haunt into Poison Frogs. Lets you weave your 3 Active haunts into the battlefield as you kill with other moves.
Wizard
Most of her's cancellables suck. The spellcasters can't really make great use of this.
She can cancel Arcane Orb and Twister, but the recovery gains aren't that great.
The best gain is on Spectral Blades, as shown in the video. This attack has almost no Startup phase, and is entirely Recovery based. So, you can cancel this into whatever. Melee-Sorc FTW.
If I was going to cancel Orb or Twister, I'd cancel into Magic Missile since it wont' cost anything at higher levels. A basic 2for1.