this page on the homebrewery

When the artificer came out, I kind of wanted to build a subclass that works with traps. Originally this focused on giving the artificer some of the rogue's kit: cunning action, and something similar to snake attack. With trying to make something that wouldn't work better as an infusion, I've taken the base of the Artillerist artificer, and turned into into a trapmaking effect. Most of the combat effects are based on using the traps, although I'm not sure what to add at 5th level that would be relevant to the class. Otherwise, I think this is odd enough that I shouldn't really commentate it.

In practice, I expect this to play more as a controller rather than the blasting Artillerist.

Ideas for additional traps and and a relevant 5th level feature.

Also known as vault breakers, these artificers focus on trapmaking, both into their construction and how to avoid those of others.

Tool Proficiency
You gain proficiency with mason's tools. If you already have this proficiency, you gain proficiency with one other type of artisanís tools of your choice.

Vault Builder Spells
You always have certain spells prepared after you reach particular levels in this class, as shown in the Artillerist Spells table. These spells count as artificer spells for you, but they donít count against the number of artificer spells you prepare.

Vault Builder Spells
Artificer Level Spell
3rd Snare, Zephyr Strike
5th Rope Trick, Lasting Acid
9th Dispel Magic
13th Grasping Vine, Wall of Fire
17th Passwall, Wall of Force

Trap Slick
When you choose this archetype at 3rd level, you gain an intimate understanding of the inner functions of traps. You gain advantage on saving throws make to avoid a trap or natural hazard.

Instant Trapper
You learned to create traps in the locations your enemies already occupy. You learn the methods for creating up to three of the following traps.

When you take the attack action, you can deploy one of the following instant traps as an attack, which appears in a space within 5 feet. You can deploy up to one of each trap you know, which remain in place for 1 hour or until you use an action to remove them. You regain the use of each trap when you use an action to disengage it or at the end of a short or long rest.

You can spend 1 minute reinforcing a trap you have deployed. While reinforced the trap lasts up to 8 hours, but you do not regain the use of this trap until you finish a short or long rest after the duration has ended.

Instant Traps
Your traps that allow a saving throw have a save DC of 8 + your proficiency modifier + your Intelligence modifier.
  • Burning Coals This trap is deployed in a 10 foot square. Any creature that enters or stops moving while inside the trap must make a Dexterity saving throw or take 3d8 fire damage. Taking this damage reduces the creature's speed by 10 feet for one minute. And the end of its turn, the creature can make a Constitution saving throw, ending the effect on a success.
  • Lighting Trap This trap emits eerie light, causing creatures and objects 10-foot-radius sphere to glow. Any creature that starts its turn inside the trap or enters it is affected as by the faerie fire spell until the end of its next turn.
  • Poison Caltrops This trap is deployed in a line 5 feet wide and 15 feet long. Any creature that enters or moves while inside the area must succeed on a DC 15 Dexterity saving throw or stop moving this turn, taking 1 piercing damage and is poisoned for one minute. Taking this damage also reduces the creature's walking speed by 10 feet until the creature takes an action to remove the caltrop. A creature moving through the area at half speed doesn't need to make the save.
  • Smoke Trap This traps billows out noxious smoke. Each creature 10-foot-radius sphere centered on the trap must make a Constitution saving throw or be blinded for 1 minute. At the end of each of its turns, the target can make another Constitution saving throw, ending the effect on a success. You automatically succeed on saving throws against this trap.
  • Sawing Trap This saw rotates in a 1 foot tall, 10-foot-radius cylinder along the ground. Each creature that enters or starts its turn in the trap's space must make a Dexterity saving throw or take 3d8 slashing damage.
  • Web Trap Each creature that starts its turn in the webs or that enters them during its turn must make a Dexterity saving throw. On a failed save, the creature is restrained as long as it remains in the webs or until it breaks free. A creature restrained by the webs can use its action to make a Strength check against your spell save DC. If it succeeds, it is no longer restrained.

Extra Attack
Starting at 6th level, you can attack twice, instead of once, whenever you take the Attack action on your turn. Moreover, when you throw a net, the short and long ranges of the net are doubled.

Viscous Traps
At 9th level, every instant trap you create is more destructive:
  • A damaging trapís damage rolls all increase by 1d8.
  • You can deploy traps within 10 feet.
  • As an action, you can command a trap to detonate if you are within 60 feet of it. Doing so destroys the trap and forces each creature inside the trap or within 5 feet of it to make a saving throw against the trap, as if they had triggered it. On a failed save the target is affected as by the trap and takes 3d8 force damage. On a success the target is unaffected by the trap and takes half as much force damage.

Master of Trapping
By 15th level, deploying traps is second nature to you. You can deploy a trap as a bonus action.

Additionally, you take half damage from all traps.