I only have two, one minor, one major.

The minor: Stacking vulnerability up debuffs. The reason why this is the minor one is, it's not a bad thing to include, I just feel like when almost every single attack from every single boss does it, it's overused.

The major: Misdirection. I'm sorry, but anything that messes with my ability to control my own movement is a cheap shot. It's fake difficulty, and flat out p---es me off every time they do it.