Expertise. Twilliam gains Expertise in two of his skill proficiencies, Stealth and Sleight of Hand

Sneak Attack. Twilliam knows how to strike subtly and exploit a foe's distraction. Once per turn he can deal an extra 3d6 damage to one creature he hits with an attack roll if he has Advantage on the roll and the attack uses a Finesse or a Ranged weapon. The extra damage's type is the same was the weapon's type. Twilliam doesn't need Advantage on the attack roll if at least one of his allies is within 5 feet of the target, the ally doesn't have the Incapacitated condition and he don't have Disadvantage on the attack roll.

Thieves' Cant. Twilliam's father taught him Thieves' Cant when he was young, using it to send him secret messages behind his mother's back. Twilliam can read and write Thieves' Cant, a secret mix of dialect, jargon, and code that allows him 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.

Weapon Mastery. Twilliam can use the weapon mastery of his daggers, Nick. When Twilliam makes the extra attack of the Light property, he can make it as part of the Attack action instead of as a Bonus Action. He can make this extra attack only once per turn.

Jumper. Twilliam determines his jump distance using his Dexterity rather than his Strength.

Cunning Strike. Twilliam has developed crafty ways to use his size to his advantage when attacking. When he uses Sneak Attack, he can add special effects to the attack at the cost of some of the damage dice. He removes the number of dice from the attack before rolling, and the effect occurs immediately after the attack's damage is dealt. The DC for these options is 15.

• Trip (Cost: 1d6). If the target is Large or smaller, it must succeed on a Dexterity saving throw or have the Prone condition.
• Withdraw (Cost: 1d6). Immediately after the attack, you move up to half your speed without provoking Opportunity Attacks.

Keen Observer. Twilliam has expertise in the Perception skill.