Increase your Wisdom score by 1, to a maximum of 20.

When sleeping or in an elven trance, gain advantage on being aware of anyone within 20 ft of you. Unless you take an action, this awareness does not interrupt sleep or alert anyone that you are not asleep. Others can't determine your awareness unless they succeed on a Wisdom (Insight) check (DC equal to your Wisdom score + your proficiency bonus).

Gain advantage on any offensive action during your first turn when attacking someone who believes you are asleep/in a trance.