Doppelganger Bushwhacker (5e Feat)

Prerequisites: You must be a doppelganger.
Your natural abilities have taught you the tactical value of surprise. You gain the following benefits:

You gain proficiency in either the Stealth skill or the Deception skill. If you are already proficient in the skill, you may double your proficiency bonus.
If you attack a surprised creature, you gain advantage on attack rolls against it and deal an additional 2d6 damage to it with weapon attacks or unarmed strikes during the first round of combat. This damage increases to 3d6 at 5th level, 4d6 at 9th level, 5d6 at 13th level, and 6d6 at 17th level.
If you take the Attack action during the first round of combat, you may make one additional attack as a bonus action.