Elise - Rappel Delay Bug
Pressing Rappel (E) instantly after changing forms (R) will not activate E for a notable time. During that time, Elise instead walks a fixed distance toward the direction of the cursor.
In order to circumvent this, players need to press E multiple times after changing forms, making playing Elise less smooth and more about smashing buttons.
This was highlighted back in 2016 but without discovery of how the bug happens. I gave the cause in this post.