Only thing I figured out on my own is that diablo is not a perfect game. That is based mostly on PvP games and I'll give some example of what I mean.
Before we start, short insight into cast mechanics in diablo. Casting spells has two parts in diablo: first part is actually casting the spell, second part is backswing animation after you have cast the spell. Or in short, first part is called "action frames", and along with second part it creates well known fcr breakpoints.
For example 200 fcr sorc. Anyone and their mom knows she has 7 frames cast rate, right? But not everyone know that inside those 7 frames there are 4 frames of actually casting the spell, and 3 frames of backswing animation. This means sorc has then action frame of 4, and after 4 frames she has complete casting the spell. Rest 3 frames she only has backswing animation once she is done casting. This is best visible with vampire necromancer who has action frame of 5 and casts nova rather quickly, but spends the other... 10 frames or whatever weaving his hand in the air doing nothing else.
Now mindblast. In PvP Mind Blast is not stunning players, it knocks them back and puts them into hit recovery instead. There is also swirly over the head of the player which remains for the duration of stun of mindblast, and as long as that swirly is there, ANY damage will put player to hit recovery. Ok ok. Let's focus on hit recovery aspect of casting Mind Blast.
Let's have 2 characters in mind now. First is 65 fcr assassin, meaning she casts Mind Blast every 11 frames. Other character is sorceress with 86 hit recovery (7 frames) and 105 fcr (action frame of 5 + backswing animation of 3 frames for a total of 8 frames per cast). So, assassin casts mindblast on sorc putting her to hit recovery. Sorc is now trying to teleport out of it, but can't because she is put into hit recovery that lasts for 7 frames. After those 7 frames, she is finally attempting to cast the teleport, and it takes her 5 frames to succeed. Oh wait, 7+5 is 12 frames, right? But assassin casts mindblast every 11 frames. This means if assassin is constantly casting mindblast, she is gonna put sorc into hit recovery every 11 frames, and for sorc it takes total of 12 frames to get out of hit recovery and finally cast teleport.
In short, sorc has no chance to cast the teleport and as long as assassin is mindblasting her, she will be constantly put into hit recovery before she manages to cast it. Diablo version of stunlock if you wish. But that is ideal situation in theory. In reality, however, assassin rarely manages to connect more than 2 mindblasts before sorc manages to teleport out of it. Sometimes as you mindblast sorc, she is just teleing around like nothing is happening. That can be explained with delay between casts if you play on someone else's host. But even if you are host, you still can't stunlock sorc that way.
So, with some theorycrafting and stuff, I figured that diablo is strange game and sometimes strange stuff happens. What I figured out on my own however is that action frame of movement is either 0 or 1 or whatever very very low value. Why? Because let's take mentioned example of mindblast on sorc. She will be put into hit recovery. But after 7 frames she is free and has 4 frames of free space to do whatever (attempting to cast spell or move around). If she is trying to run instead of teleport, she will simply run those 4 frames before she is put into another hit recovery. Cool, right?
You thought stuff I'm talking about is confusing? Just wait until I tell you what I tested next. Sorceress with 0 FHR has incredible 15 frames hit recovery. This means when something puts her to hit recovery, she is completely helpless for 15 frames and can't do a thing in that period. So I have tested the following: 0 FHR sorc that is surrounded by 2 wake of fire + 3 lightning sentries + she has mindblast over her head meaning she is put to hit recovery whenever she is hit.
Theory say: There is no way in the world mentioned sorc should be able to move. She must be completely frozen in time, helpless as long as at least wake of fires are up.
Reality: mentioned sorc had very hard time to move, but she did move inside those traps. Even if I put 3 wake of fire + 2 sentries, she is still able to move around. 15 frames hit recovery, yeah right, give me a break.
My explanation of that confusing test is the following: when character is put to hit recovery in diablo, he can't be put into hit recovery again until hit recovery time is up. That means that first time sorc is hit with whatever, she is put into 15 frames hit recovery period. In that period, whatever hits her, hit recovery "timer" is not reset, meaning any hit inside that 15 frames period won't put her into hit recovery again. To have permastun effect, something must hit that sorc either exactly at 15th frame of her hit recovery, of 1 frame later. Otherwise her hit recovery timer will be up and she will have space to move until she is hit again. That's my conclusion according to tests.
If same thing applies to say block recovery, those two things can explain how is it possible to teleport out of fanaticism pack who is beating the daylight out of you, and you instead of being stuck into block/hit recovery, you manage to teleport out like a boss. Next question is do hit recovery caused by damage and hit recovery caused by mindblast same in nature. In short, what if there comes freaky berserk barb and zerks sorc doing 2k damage to her at 14th frame of her hit recovery, would then the timer of hit recovery reset, or would sorc still be able to move?
Anyway, those were some of my tests and discoveries. Thank you for not reading and cya around.
tl;dr be useful and go make me a sandwich
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