There is no player who has read all the books and knows all the powers from memory.
That is why upon using a supernatural power in game you are obligated to give a clear description of the power to all the involved players. Don't use a certain power if you are not sure how does the system for that power work. If the power may affect future roleplays, you must take a SS of where the /ictime and/or /servertime is visible along with the details that would explain how did your character exactly use the power.
E.g. if your character has an active Unseen Presence (Obfuscate Discipline level 3 power) and you jump down the roof and failed the Wits + Stealth roll to remain concealed, you are obligated to let the nearby players know they can roll Wits + Alertness difficulty 7 to set their characters free from the mental haze of the power completely.