[GAMEPLAY] Syndra Stun Bug Finally Unraveled
I finally unraveled the mystery of why Syndra's stun has historically been so randomly buggy in no reproducible way, including why the changes to E's width had such a drastic effect on it's reliability (aside from just being harder to land).
I wrote up a detailed explanation on the Reign of Gaming forums here: http://www.reignofgaming.net/forums/league-of-legends/general-discussions/104474-syndras-e-has-always-been-so-buggy-and-now-i-know
I've quoted the post below:
Oh lawdie. I just figured it out. I think I know why Syndra's E has always been so buggy. Not just the current smaller-than-it-should-be hitbox, but all the times we've watching an orb go straight through someone without a stun prior to those nerfs.
Okay, so Imma break this down in non programmer terms as much as I can.
Think of league's game engine as a movie. Each frame is a little bit of motion. Add a whole bunch of frames together and we get what appears to be a flowing, continuous experience we call a game.
The difference is between a game engine and a movie is that the time between "frames" is variable. How far has the skillshot traveled between one frame is just mathematically calculated using the time passed. If somethings moving in a given direction (north) at a given speed (60km/h) and we know how much time has passed (1 hour), then it's very simple to figure out the new location of the object (60km north of where it was).
So normally we just use the same math for a skill shot. It's the same, simple calculations. You're just moving a rectangle (hitbox) in a straight line. If something's in the hitbox, it gets hit.
With me so far?
Now for the quote from the most recent patch notes: THERE'S SOME COMPLICATED MATH BELOW Collision width of Dark Spheres has been increased. The reason we say complicated math is because this spell operates on multiple targeting / collision radius checks, and explaining each one gets... well, complicated. Hopefully we can just say it's wider and your experience will be more reliable. Here's the catch with Syndra's E. Riot's not moving a single, rectangular hitbox. They're moving an actual orb and using that. Why does that matter? First off, the orb is considered, for intents and purposes, an untargetable unit. Moving a unit is going to require more processing power than a hitbox. On top of this, every orb and every unit hit is considered a projectile. Meaning the problem is multiplied. And every unit hit with the stun is slightly displaced. More processing!
But why does this processing power even matter? Because, as I said before, the time between "frames" in the game isn't constant. How long each frame takes depends on how busy the CPU is. The busier the CPU, the longer the time between frames. This means that, because the orb is pretty fast, it could potentially move entirely past its target in a single frame if the CPU were busy enough.
And we're creating the need for a whole bunch of calculations during the E. That's gonna keep the CPU pretty busy.
Let me illustrate (in beautiful MS paint):
http://i.imgur.com/JZJkiJR.png
NOTE: This is image is not to scale and is an extreme example. The chances of it passing over the middle of a champion are slim. But it could easily happen over one of the edges of a champion (a shorter distance to skip over).
In picture number 1, the skill works entirely as expected. In picture two, there's enough going on in your game (and all the other games on that server) to cause just a tiny amount of "lag." This type of lag would be pretty unnoticeable to the player... except when something like this happened.
In addition to this, we're dealing with circular hitboxes instead of rectangles, creating a double-whammy. The series of circles make a much patchier hitbox. To demonstrate I'll once again show off my artistic abilities:
http://i.imgur.com/myMvhDN.png
The skill is extremely computationally expensive (especially if we're talking about Eing through a wave of minions), and is extremely prone to the effects of CPU "lag" because it's high velocity. The skill has a less-than-ideal hitbox that exacerbates these problems.
End result? A skill that occasionally doesn't work - but in a very inconsistent, nearly impossible to reproduce way. If there happens to be a whole bunch of teamfights going on in other games on the server when you go to E through a minion wave, you could be left with an E that doesn't proc.
The solution for riot's programmers is relatively simple. If E hit's an orb, generate a rectangular hitbox like Lux's Q. Remove the orb from the field (without decreasing ult counter of course), create the particle effect, recreate orb at end of the skill. Now E is just as consistent as every other skillshot and you can play with the width all you want without messing up reliability.
TL;DR: I'm a nerd, rectangles are better than circles, Riot should give me a Syndra/orb summoner icon for figuring out such a long standing bug, and the reason your stun didn't proc is because other people are playing other games on the same server as you.
