Pyromaniac

A small gnome sits on a wooden log in the forest that rests near their party's campfire. It's their watch for the night, and the other members are resting peacefully in their bedrolls. The gnome stares into the swirling flames of the fire for a moment, before feeling themselves hit with a sudden burst of inspiration. They reach into their bag, pull out the tools of their craft, and begin fiddling with them intensely. The night passes by, before the gnome finally completes their project: a small bundle of explosive material, ready to be ignited at their command. A breeze begins to gently blow through the area, as if to calmly reassure the nearby trees that no harm shall befall them. The gnome smiles wickedly, and places the explosive into their bag. Woe be to the next person to find themselves at the gnome's mercy. 

Those who choose the life of a rogue do so for many different reasons. Some wish to lurk amongst the shadows, scavenging through lavish homes in the dark of night for coin and valuables. Others don't mind shedding a bit of blood for profit, selling their deadly services to those who are willing to pay. A few, however, just want an excuse to blow stuff up and watch it burn to the ground. You happen to be one of those people. As a Pyromaniac rogue, you will become a master of the inferno, utilizing your craft to create potent explosives, ignite your foes with your attacks, and instill fear in any who are foolish enough to get on your bad side.

Pyromancy

Starting at 3rd level, you gain the ability to tinker with flammable and explosive material to your benefit. You gain proficiency with Tinkerer’s Tools, if you don’t already have them.

In addition, you learn a small list of craftable items to aid you. With one hour of work using your tinkerer's tools, you can craft one item from the list, so long as you expend the appropriate cost requirements. These cost represents material components needed to craft the item. If your DM approves, you can also make your own items to add to the list. 

Some of your class features and items require your target to make a saving throw to resist the feature's effect. The saving throw DC is calculated as follows: 

Pyromaniac save DC: 8 + Proficiency Bonus + your Intelligence modifier

Craftable Items

Firebomb (Cost: 30g): As an action, you can throw the firebomb to a location within 60ft of you. Each creature within 10ft of the explosion must make a Dexterity Saving Throw. On a failed save, a creature takes 3d6 fire damage, and half on a successful save. Additionally, any flammable objects out in the open within the explosion radius are set on fire until the end of your next turn, including items that are worn or carried. A creature that is wearing or holding an ignited object takes 1d6 Fire damage at the start of your next turn, unless it uses its acton to put the fire out or drops the item, if it can. 

Molotov (Cost: 50g): As an action, you can throw a molotov to a location within 60ft of you. The area becomes engulfed in flame in a 10ft radius from the chosen landing spot. Whenever a creature starts its turn in the engulfed space, or enters it for the first time on its turn, it takes 2d6 fire damage. This effect lasts until the end of your next turn. 

Concussion Bomb (Cost: 80g): As an action, you can throw a concussion bomb to a location within 30ft of you. The bomb stays in the spot it is thrown to unless a creature chooses to move it, or you use your bonus action to detonate it. Upon detonation, each creature within 10ft of the bomb must make a Strength Saving Throw or be pushed 20ft away from it. A creature can choose to fail this saving throw. When you gain the Arsonist subclass feature, you can detonate your concussion bomb as a free action. 

Combustive Nature

Also at 3rd level, you’ve learnt how to apply your fiery and explosive skills in combat. Whenever you hit a creature with a regular attack, you can use your bonus action to apply one of the following effects. 

Explosive Knockback: The creature must make a Dexterity Saving Throw against your DC or be pushed up to 10ft away from you.

Lingering Embers: The creature becomes ignited with a slow burning flame. The flame goes out if it comes into contact with water or a strong wind. At the start of the creature's turn, they take 1d4 fire damage. This effect lasts until the flame is put out naturally, the creature uses its action to put the flame out, or you apply another effect against a creature. 

Distracting Flare: The creature must make a Wisdom Saving Throw. On a failure, it can't take reactions until the end of your next turn. 

Burning Blood

At 9th level, you've spent so much time around blazing material that its effects on you are weakened. You gain resistance to Fire damage. In addition, whenever you use your uncanny dodge to reduce damage from a creature's attack, you deal fire damage towards the creature that equals half your rogue level (rounded up), so long as the creature is within 5ft of you. 

Arsonist

At 13th level, you've become a master of your craft, and learn to make and use your creations more effectively. The cost of all items on your craftable list is halved, and your items are considered magical for the purpose of overcoming resistances. In addition, you can use an item as a bonus action, rather than an action, on your turn. 

Staring into the Inferno

At 17th level, you have become one with fire. You become immune to Fire damage. In addition, you can use your action to stare into the eyes of your enemies, and give them a brief glimpse of the pure destruction you are capable of. All hostile creatures within 60ft of you and can see you must make a Wisdom Saving Throw. For 1 minute, or until you lose concentration (as if you were casting a concentration spell), each creature that fails becomes Frightened of you. A creature who succeeds on this saving throw is immune to your stare for 24 hours. Once you use this feature, you can not use it again until you finish a long rest.