At 1st level, your proficiency bonus is doubled for any ability check you make that use Perception or Steath.
At 6th level, you can choose two more of your proficiencies (in skills or with thieves' tools) to gain this benefit.

Beginning at 1st level, you know how to strike subtly and exploit a foe's distraction. Once per turn, you can deal an extra 3d6 damage to one creature you hit with an attack if you have advantage on the attack roll. The attack must use a finesse or a ranged weapon.

You don't need advantage on the attack roll if another enemy of the target is within 5 feet of it, that enemy isn't incapacitated, and you don't have disadvantage on the attack roll.

During your rogue training you learned thieves' cant, a secret mix of dialect, jargon, and code that allows you to hide messages in seemingly normal conversation. Only another creature that knows thieves' cant understands such messages. It takes four times longer to convey such a message than it does to speak the same idea plainly.

In addition, you understand a set of secret signs and symbols used to convey short, simple messages, such as whether an area is dangerous or the territory of a thieves' guild, whether loot is nearby, or whether the people in an area are easy marks or will provide a safe house for thieves on the run.

You hone your skills in the larcenous arts. Burglars, bandits, cutpurses, and other criminals typically follow this archetype, but so do rogues who prefer to think of themselves as professional treasure seekers, explorers, delvers, and investigators. In addition to improving your agility and stealth, you learn skills useful for delving into ancient ruins, reading unfamiliar languages, and using magic items you normally couldn't employ.

Starting at 3rd level, you can use the bonus action granted by your Cunning Action to make a Dexterity (Sleight of Hand) check, use your thieves' tools to disarm a trap or open a lock, or take the Use an Object action.

When you choose this archetype at 3rd level, you gain the ability to climb faster than normal; climbing no longer costs you extra movement.

In addition, when you make a running jump, the distance you cover increases by a number of feet equal to your Dexterity modifier.

As a bonus action, you give yourself advantage on your next attack roll on the current turn. You can use this bonus action only if you haven't moved during this turn, and after you use the bonus action, your speed is 0 until the end of the current turn.

The accuracy of elves is legendary, especially that of elf archers and spellcasters. You have uncanny aim with attacks that rely on precision rather than brute force. You gain the following benefits:

Increase your Dexterity by 1, to a maximum of 20.

Whenever you have advantage on an attack roll using Dexterity, Intelligence, Wisdom, or Charisma, you can reroll one of the dice once.

Starting at 5th level, when an attacker that you can see hits you with an attack, you can use your reaction to halve the attack's damage against you.

Beginning at 1st level, you have significant experience studying, tracking, hunting, and even talking to a certain type of enemy commonly encountered in the wilds. Choose a type of favored enemy: undead. You gain a +2 bonus to damage rolls with weapon attacks against creatures of the chosen type. Additionally, you have advantage on Wisdom (Survival) checks to track your favored enemies, as well as on Intelligence checks to recall information about them. When you gain this feature, you also learn one language of your choice, Deep Speech.

You area master of navigating the natural world, and you react with swift and decisive action when attacked.This grants you the following benefits:
•You ignore difficult terrain.
•You have advantage on initiative rolls.
•On your first turn during combat, you have advantage on attack rolls against creatures that have not yet acted.
In addition, you are skilled at navigating the wilderness. You gain the following benefits when traveling for an hour or more:
•Difficult terrain doesn’t slow your group’s travel.
•Your group can’t become lost except by magical means.
•Even when you are engaged in another activity while traveling(such as foraging, navigating, or tracking), you remain alert to danger.
•If you are traveling alone, you can move stealthily at a normal pace.
•When you forage, you find twice as much food as you normally would.
•While tracking other creatures, you also learn their exact number, their sizes, and how long ago they passed through the area.

You gain proficiency in Insight and Perception

You gain proficiency in Lutes and Dice Sets

You can speak, read, and write Sylvan

Your accent, mannerisms, figures of speech, and perhaps even your appearance all mark you as foreign. Curious glances are directed your way wherever you go, which can be a nuisance, but you also gain the friendly interest of scholars and others intrigued by far-off lands, to say nothing of everyday folk who are eager to hear stories of your homeland.

You can parley this attention into access to people and places you might not otherwise have, for you and your traveling companions. Noble lords, scholars, and merchant princes, to name a few, might be interested in hearing about your distant homeland and people.

Thanks to your elf blood, 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 advantage on saving throws against being charmed, and magic can't put you to sleep.

Your base walking speed increases to 35 feet.

You can speak, read, and write Common, Elvish, and Primordial