Whistler can use a bonus action to inspire a creature within range that can hear him. The creature gains a Bardic Inspiration die, a d8, which it can use for qualifying ability checks, attack rolls, or saving throws. He has four uses, regained on a long rest, and Font of Inspiration allows him to regain uses through spell slots or a short rest.

Whistler can regain expended Bardic Inspiration uses after a Short or Long Rest. He can also expend a spell slot as a bonus action to regain one expended use, with the number of uses determined by the slot's level.

Whistler can use a reaction to prevent a creature within range from becoming Charmed or Frightened. If the creature is already Charmed or Frightened, he can suppress that condition for one minute.

Whistler makes a weapon attack using his rapier or dagger.

Whistler spends a Bardic Inspiration use to empower an ally or hinder an enemy through his music and cutting remarks.

Whistler is a full spellcaster using Charisma as his spellcasting ability. He can cast bard spells using spell slots and can use a musical instrument as a spellcasting focus.

Whistler has Expertise in Deception and Performance, doubling his proficiency bonus for those skills.

Whistler adds half his proficiency bonus to ability checks that do not already include his proficiency bonus.

Whistler chooses the College of Lore, gaining additional skill proficiencies and the ability to undermine enemies with cutting remarks.

Whistler can use his reaction when a creature he can see within range succeeds on an attack roll, ability check, or damage roll. He expends a Bardic Inspiration die and subtracts the result from the roll, potentially turning success into failure.

Whistler gains an Ability Score Improvement or an eligible feat. His final ability scores reflect his completed ability score choices.

Whistler gains proficiency in three additional skills of his choice. These are Investigation, Persuasion, and Sleight of Hand, though Sleight of Hand proficiency is already supplied by his background and is counted only once.

Whistler learns two spells from any class's spell list. These spells count as bard spells for him and can be replaced when he gains a Bard level.

Whistler gains another Ability Score Improvement or an eligible feat. His final ability scores reflect his completed ability score choices.

Whistler gains Expertise in two additional proficient skills, doubling his proficiency bonus for those skills. He has chosen Sleight of Hand and Stealth.

Whistler has a reliable criminal contact who can provide information, introduce him to underworld figures, or pass along messages. His criminal past also gives him familiarity with secrecy, coded communication, and the habits of guards and thieves.