Some effects cause a creature to be possessed by another creature or entity. A possessing effect defines how the possession operates. Possession can be prevented by the Protection from Evil and Good spell and ended by the Dispel Evil and Good spell. Proficiency If you have proficiency with something, you can add your Proficiency Bonus to any D20 Test you make using that thing. A creature might have proficiency in a skill or saving throw or with a weapon or tool. See also “Playing the Game” (“Proficiency”).