Saboteur

This subclass largely focuses on explosives, their crafting, ability to do damage, and your own resistance to it. 

Explosives:

Bomb- Mundane Item (Explosive), 1 pound.

As an action, a creature can light this bomb and throw it at a point up to 60 feet away. Each creature within 5 feet of that point must succeed on a Dexterity saving throw or take 3d6 fire damage.

Dynamite- Mundane Item (Explosive), 1 pound

As an action, a creature can light a stick of dynamite and throw it at a pint up to 60 feet away. Each creature within 5 feet of that point must succeed on a Dexterity saving throw, taking 3d6 bludgeoning damage on a failed save, or half as much on a successful one. 

A character can bind sticks of dynamite together so they explode at the same time. Each additional stick increases the damage by 1d6 (to a maximum of 10d6) and the burst radius by 5 feet (to a maximum of 20 feet).

Dynamite can be rigged with a longer fuse to explode after a set amount of time, usually 1 to 6 rounds. Roll initiative for the dynamite. After the set number of rounds goes by, the dynamite explodes on that initiative.

Gunpowder- Mundane Item (Explosive), 1 pound

Setting fire to a container full of gunpowder can cause it to explode, dealing 3d6 fire damage to creatures within 10 feet of it. A successful Dexterity saving throw halves the damage. Setting fire to an ounce of gunpowder causes it to flare for 1 round, shedding bright light in a 30 foot radius, and dim light for an additional 30 feet.

Alchemical Knowledge

When you choose this archetype at 3rd level, you gain proficiency with Alchemist's Supplies. In addition, your skill with this tool allows you to spend an action to replicate the effects of the Pyrotechnics spell an amount of times per day equal to your proficiency bonus, but as a ranged weapon attack (20/60). The saving throw is equal to your explosives saving throw.

Explosive Savant

Starting at 3rd level, you have the knowledge to craft your own explosives. After completing a long rest, you are able to craft a number of explosives equal to your intelligence modifier (minimum of 1), of your choice between gunpowder, bomb, or dynamite. For example, with an Intelligence modifier of 3, you can craft 2 bombs and 1 dynamite, etc. You can also expend hit dice during a short rest to craft an additional explosive, up to a maximum equal to half your proficiency bonus, rounded down.

The saving throw for your explosives is calculated as follows:

Save DC = 8 + your proficiency bonus + your Intelligence modifier

You also gain a new way to use sneak attack. In addition to other uses of sneak attack, if a creature fails its saving throw by 5 or more, you can add sneak attack damage to the throw.

The damage of each explosive goes up by 1d6 at 9th level, and again at 13th and 17th.

Enhanced Explosions

At 9th level your skill at crafting explosives increases substantially. The damage from your explosives now counts as magical for the purposes of overcoming resistance and immunity to nonmagical damage. Additionally, you can now throw an explosive as a bonus action instead of an action.

Explosives Expert

By 13th level your skill with explosives has taught you several ways to increase their effectiveness, and to reduce the danger of using them. You gain the following benefits:

• You have resistance to damage dealt by your own explosions
• You can rig the fuse of your explosives to act under varying circumstances, exploding from a trip wire or a fuse of up to ten minutes.
• Your explosives now always deal maximum damage against objects and structures.

Master of Destruction

Upon reaching 17th level, your ability to cause destruction has increased tenfold. You gain the following benefits:

• Once per day, after crafting explosives, you can roll 1d4, gaining that many more explosives of your choice.
• Whenever you attack using an explosive, you can choose to throw two instead of one.
• You can now change the damage type of bombs upon crafting them. Choose between Fire, Cold, Thunder, and Force damage.