3rd level — Fast Hands

Use the Cunning Action bonus action for Sleight of Hand, thieves' tools to disarm traps or open locks, or the 2014 Use an Object action.

3rd level — Second-Story Work

Climbing no longer costs extra movement, and running jumps gain additional distance based on Dexterity.

9th level — Supreme Sneak

Gain advantage on Dexterity (Stealth) checks when you move no more than half your speed during the same turn.

13th level — Use Magic Device

Ignore class, race and level requirements for using magic items.

17th level — Thief's Reflexes

Take two turns during the first round of combat, with the second turn occurring at initiative minus 10; the feature cannot be used while surprised.

How the features work together

Thief is strongest when the player treats the environment as part of the character sheet. Fast Hands can manipulate useful mundane gear or locks without sacrificing the main action, Second-Story Work opens vertical routes, and Supreme Sneak supports careful infiltration. At high level, Use Magic Device dramatically broadens the equipment that can become part of the Rogue's toolkit.