Blinding Sneak Attack

Prerequisite: Tiefling
You are one with the darkness and the shadows can consume the enemy. You gain the following:

• Increase your Dexterity score by 1.
• If you attack a creature who has not taken their first turn in a combat, the attack deals an extra 2d6 necrotitc damage to it. The creature must make a Constituion saving throw (DC 10 + the 2d6 damage) or is temporarily blind for 1 round.