Mannahnin
Scion of Murgen (He/Him)
I believe Max is correct on this one. in 5E, you don't get to interrupt an action mid-resolution with a Readied action. If you declare someone taking an action to be your trigger, you have to wait until after the action resolves. You can't break into the middle of it between declaration and resolution.Which part of "If the reaction interrupts another creature's turn, that creature can continue its turn right after the reaction." causes a problem to you ? I interrupt a creature between his declaration that he intends to attack me and the actual attack and its resolution. I nullify the attack, because when he resumes his attack, I am no longer a valid target.
You have declared an attack (probably swinging your sword in my direction), this is obviously perceivable, and therefore a valid trigger, so misty step goes off, interrupting the rest of the attack sequence. 100. %. RAW.
You could declare a Readied Misty Step to teleport away if the person moves into melee reach, however. They would be able to continue moving once your Readied action was completed, but if they didn't have enough movement left to get back into melee range, you would have foiled their attempt to attack you.