Roll a d20, If it is higher then a 14 then you can blend in with the environment, making it almost for someone to find you. If you are successful add an advantage to stealth until you come out of hiding. (lasts 3 turns) 

You have proficiencies in the short sword, and the short bow.

Proficiency in Stealth. 

This Elf race gets a small strength boost.

Stealth Advantage

Add +2 to dex and chose +1 for one additional ability.

Unlike the usual Elf, this race ages like the human race.

This Elves usually like to stay in shadows when possible, and because of this a lot of assassin is work done is by this unusual race of Elf. They're usual in a chaotic neutral alignment.

These Elves range from 3' 4"  to 4' 9" feet tall and have slender builds. Your size is Small.

Your base walking speed is 20 feet.

Accustomed to twilit forests and the night sky, you have superior vision in dark and dim conditions. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can’t discern color in darkness, only shades of gray.

You have proficiency in the Perception skill.

You have advantage on saving throws against being charmed, and magic can’t put you to sleep.

Elves don’t need to sleep. Instead, they meditate deeply, remaining semiconscious, for 4 hours a day. (The Common word for such meditation is “trance.”) While meditating, you can dream after a fashion; such dreams are actually mental exercises that have become reflexive through years of practice. After resting in this way, you gain the same benefit that a human does from 8 hours of sleep.

You can speak, read, and write Common and Elvish. Elvish is fluid, with subtle intonations and intricate grammar. Elven literature is rich and varied, and their songs and poems are famous among other races. Many bards learn their language so they can add Elvish ballads to their repertoires.