Sapper

A Sapper is a recently-developed branch of artifice focused on the territorial aspects of war. If the terrain that a battle will take place on isn't ideal for your side, sappers can fix it.

Source: The Sharpest Tools - 16 Artificer Subclasses by 3athompson on GM Binder

Tool Proficiency

You gain proficiency with carpenter's tools. If you already have this proficiency, you gain proficiency with one other type of artisan’s tools of your choice.

Sapper Spells

You always have certain spells prepared after you reach particular levels in this class, as shown in the Sapper Spells table. These spells count as artificer spells for you, but they don’t count against the number of artificer spells you prepare.

Wall of Wood

Your artifice allows you to spontaneously bring plant matter into existence to reinforce your position. Using carpenter's tools, you can take an action to magically create wooden reinforcements at an unoccupied space you choose within 5 feet of you. You create a wall that is 3 inches thick and is composed of a number of 10-foot-by-10-foot panels equal to your artificer level. Each panel must be contiguous with at least one other panel. The wall can only be created in unoccupied spaces.

The wall can have any shape you desire, though it can't occupy the same space as a creature or object. The wall doesn't need to be vertical or rest on any firm foundation. It must, however, be solidly supported by solid ground. Thus, you can use this feature to bridge a chasm or create a ramp. If you create a span greater than 20 feet in length, you must halve the size of each panel to create supports.

The wall is an object made of wood that can be damaged and thus breached. Each panel has AC 15, hit points equal to five times your artificer level, and vulnerability to fire damage. Reducing a panel to 0 hit points destroys it and might cause connected panels to collapse at the GM's discretion. The wall of wood disappears after 10 minutes. You can dismiss it early as an action.

Once you create a wall of wood, you can’t do so again until you finish a long rest or until you expend a spell slot of 1st level or higher. You can have only one wall of wood at a time and can’t create one while an existing wall of wood is present.

When you create the wall of wood, you decide which type it is, choosing from the options on the Wall of Wood table.

Resonant Demolisher

You can make a conduit for your destruction. When you finish a long rest, you can use thieves' tools or tinker’s tools to carve special sigils into a warhammer, war pick, or maul and thereby turn it into your resonant demolisher. The sigils disappear from the object if you later carve them on a different item. The sigils otherwise last indefinitely.

You are considered proficient with your resonant demolisher, which is a magic weapon that uses your Intelligence modifier, instead of Strength or Dexterity modifier, for the attack and damage rolls. You can also use your resonant demolisher as a spellcasting focus for your artificer spells. Once on each of your turns when you hit a creature or object with your resonant demolisher, you can cause the attack to deal an extra 1d12 thunder damage to the target. The thunder damage increases when you reach certain levels in this class, increasing to 2d12 at 9th level, and 3d12 at 15th level. The resonant demolisher deals double damage to objects that are not made out of adamantine.

Booby Trap

• When you create the wall, you may create difficult terrain within 10 feet of one side of the wall of wood. When a creature moves into or within the the difficult terrain, it takes 2d4 piercing damage for every 5 feet it travels.
• As an action, you can magically cause the wall of wood to explode into shrapnel if you are within 60 feet of it. Each creature within 10 feet of the wall must make a Dexterity saving throw against your spell DC, taking 8d4 magical piercing damage on a failed save, or half as much on a successful one. The damage increases to 12d4 at 15th level.

Wallbreaker

• While you hold your resonant demolisher, you have a burrow speed of 10 feet. You can burrow through solid nonmagical rock at half your burrowing speed and you leave a 5-foot-diameter tunnel in your wake.
• You can cast passwall and move earth without expending a spell slot, without preparing the spell, and without material components, provided you use your resonant demolisher as the spellcasting focus. Once you cast either spell with this feature, you can’t cast that spell with it again until you finish a long rest.