Where most rogues excel in solving problems discretely, an arsonist has a knack for burning through challenges, quite literally.

Fervor of the Fire

When you choose this archetype at 3rd level, you gain proficiency with alchemist's supplies and alchemist's fire. You can use alchemist's supplies to craft one flask of alchemist's fire during a long rest. You still require the normal gold or materials to craft it.

In addition, you can use the bonus action granted by your Cunning Action to use a flask of alchemist's fire.

Arsonist's Arcana

At 3rd level, you learn the cantrip produce flame, and you can use the cantrip to perform additional tasks. Your spellcasting modifier when using this feature is Intelligence.

When you cast produce flame, you can perform the following additional tasks:

• You can use the flame to boil or heat a container of liquid or combust an exposed, flammable solid or liquid.
• If you use the flame to superheat a flask of alchemist's fire, the damage dice of the flask of alchemist's fire becomes equal to the damage the spell deals as an attack in the spell’s description.
• You can spread the flame to encompass a single weapon you are holding that is made of metal. The flame surrounds the weapon and changes the damage dice of the next melee or ranged attack with that weapon to fire damage equal to the damage the spell deals as an attack in the spell’s description.

You have a number of uses of this feature equal to your Intelligence modifier, minimum of 1, and all expended uses are regained after a long rest

Arsonist's Ambush

Starting at 9th level, you know how to turn pyrotechnics into brilliant distractions. You have advantage on Dexterity (Stealth) checks if you created an explosion or fire on the same turn.

In addition, if you created an explosion or fire at least 10 feet away from an enemy, you can sneak attack that enemy, as long as you don't have disadvantage on the attack.

Fire Fanatic

By 13th level, your mastery of the innate arcana from your produce flame has granted you additional spells. You learn the spells burning hands and fireball. You can cast burning hands as a 1st level spell and fireball as a 3rd level spell. You do not require a spell slot, and you use Intelligence as your spellcasting modifier. You can cast each of these spells once using this feature, and you regain their use on a short rest.

Potent Pyromania

When you reach 17th level, your craze for fire has reached a hellish enthusiasm. Whenever you deal fire damage to a creature, you can choose to enter mania as a bonus action.

While manic, fire damage you deal is doubled and you have resistance to fire damage.

Your tunnel vision makes you oblivious to surrounding danger. Creatures have advantage against you on melee weapon attacks, and you have disadvantage on Wisdom (Perception) checks.

If you are able to cast spells, you can’t concentrate on them while manic.

Your mania lasts for 1 minute. It ends early if you are knocked unconscious or if your turn ends and you haven’t created an explosion, dealt fire damage, or created a fire since your last turn.

Once you have entered mania, you can't do so again until you finish a long rest.