Far Sight

As a consequence of staring too deeply into the darkest depths of the abyss, your mind has been scarred and your perception of darkness itself has been warped. You gain Darkvision out to a range of 90 feet. If you already have Darkvision from your race, its range increases by 30 feet.

Additionally, whenever you make a Wisdom (Perception) check that relies on sight, you can choose to attempt to peer deeper than most would.

Make a DC 15 Intelligence saving throw. On a success, you gain a +10 bonus to your Wisdom (Perception) check. On a failure, your mind is racked by the sight of things meant to remain unseen and you gain a short-term madness, which only fades after 1 minute. If you fail your attempt to peer deeper while you are already affected by madness, your madness level and the time for which you are affected increases as normal, progressing from short-term, to long-term, to indefinite madness.

(The rules for Madness, as well as the tables for determining the effect of madness, can be found on page 259-260 of the Dungeon Master's Guide)