I believe that it has to do with Initiative stat and Characters Position :)

http://image.prntscr.com/image/318ee519df8144d0bf7811cb6b88889e.png

thanks. didn't thought about positioning effects priority in skill use.

What affect initiative then? Attack status?

when you Refine your eqipment it gives Initiative stats

Can you repost, how it's decided, I don't see because it says guy who said it is banned.

no it's not initiative.. already tried with my friends bcs i thought that too.. auto pvp on both side.. mine is higher than him.. sometimes i skill first sometimes he skill first when we rematch again and again.. i don't even know why.. and when i do the group convoy, me level 47 fighting with level 36.. still the level 36 skill me first.. so admin please come here and explain..

Now im even more confused <:3_44:>

Casting order is determined by your initiative.

The description of initiative is very vague on here, but it really just means the order of your attack.
You can level it by refining for now and later by eight inner gates and other things.

And also attacking order is affected by the position of your ninjas on your team,
for instance even if the initiative of your ninja on position/"move" 3 is a lot higher than your opponent, you still cannot attack before their ninja on position/"move" 1 use their mystery.

This is why for most times you should let your ninja thats on move 1 to have the highest initiative

that's a really clear description. thanks.

no problem, and also i forgot earlier,
mysteries with the label will work before normal mysteries as well.

thanks again :D