Otherworldly Draw

As an action or a bonus action, you can draw out any official monsters within D&D beyond that has a challenger rate number equal to your level ( lvl. 10 = Challenger 10 ) and use one of their attacks. It must be an action from the monster's sheet.

If you are Level 20, you can choose monsters with a challenger rate up to 30.

You can only use this once per long rest.