Recently I've been dabbling in making a few different artificer subclasses, and one that I've come to like is one that focuses on elemental magic. Since this would be my first artificer subclass I was wonder what other people thought about it so far and what they think needs to be changed, added or removed. I currently don't have much, if any flavor text at the moment, so keep that mind. In short, this subclass focuses on use and alter chromatic spells/weapon damage, and how I have it built, it can be a pseudomartial or like the artillerist, can focus on being a cantrip blaster too. So just let me know what you guys think about this so far, and hope you enjoy it.

 Edit: See below for most up to date version

Quote from FallenPhoenixIV >>

 Elemental Conduit
At 3rd level, during a long rest, you can spend 1 hour to use your Jeweler's Tools to inscribe a weapon, or piece of armor, that you are proficient with to become an Elemental Conduit. You can use the Elemental Conduit as a spellcasting focus for you, and if the conduit is a weapon, when you attack with that weapon, you can use your Intelligence modifier, instead of Strength or Dexterity, for the attack and damage rolls. If the conduit is a piece of armor, you gain a +1 you saving throws against spells or other magical effects. While you have your elemental conduit, when you cast a spell or hit with a weapon that deals acids, cold, fire, lightning, poison or thunder damage, you can spend your bonus action to substitute that damage for any other damage type from that list. The inscriptions will disappear from the object if you later inscribe a different item. The inscription otherwise last indefinitely.

 Also, is there a way to do this functionality without it applying to all weapons, like the hex blade or is this something that I have to have players make on their own?

After some more tinkering with the class, this is where I'm currently standing with it. Please let me know what you think about it.

Tool Proficiency
When you adopt this specialization at 3rd level, you gain proficiency with Jeweler's Tools. If you already have this proficiency, you gain proficiency with one other type of artisan’s tools of your choice.

Elementalist Spells
Starting at 3rd level, you always have certain spells prepared after you reach particular levels in this class, as shown in the Elementalist Spells table. These spells count as artificer spells for you, but they don’t count against the number of artificer spells you prepare.

Elementalist Spells
3rd - Absorb Elements, Chromatic Orb

5th - Acid Arrow, Scorching Ray

9th - Elemental Weapon, Fireball

13th - Elemental Bane, Fire Shield

17th - Cone of Cold, Conjure Elemental

Elemental Conduit
At 3rd level, you have learned how to manipulate the elements. Using your Jeweler's Tools, during a long rest you can inscribe a magical enchantment on your choice of a weapon, armor, or shield that you are proficient with, turning the item into an Elemental Conduit. You can use the Elemental Conduit as a spellcasting focus for you, and when you cast a spell or hit with a weapon that deals acids, cold, fire, lightning, or thunder damage, you can spend your bonus action to substitute that damage for any other damage type from that list. Depending on item you chose to become an elemental conduit, the item gains additional benefits;

• If elemental conduit is a weapon, when you attack with that weapon, you can use your Intelligence modifier, instead of Strength or Dexterity, for the attack and damage rolls. The weapon also gains a +1 bonus to its attack and damage rolls.
• If the elemental conduit is an armor or shield, you gain a +1 to your saving throws against spells or other magical effects.

You can only have one elemental conduit at a time, the inscriptions will disappear from the object if you later inscribe a different item. The inscription otherwise last indefinitely. In addition, you learn one of the following cantrips; Control Flames, Gust, Mold Earth, or Shape Water. At the end of a short rest, you can exchange the chosen cantrip for another from this list. If they don’t appear on the artificer spell list, they are nonetheless artificer spells for you.

Amplify Elements
At 5th level, when you cast a spell or hit with a weapon that deals acid, cold, fire, lightning, poison or thunder damage, you can add your Intelligence modifier to one damage roll.

Conduit Enhancement
Starting at 9th level, you've increase the capability of your elemental conduit, you gain the following benefits;

• After you finish a long rest, choose one of the following damage types to gain resistance against: acids, cold, fire, lightning, or thunder.
• The item bonuses to your elemental conduit increases to +2.

Elemental Mastery
Starting at 15th level, you have found how to push your elemental conduit beyond it's limits. You can cast Investiture of flame, Investiture of Ice, Investiture of Stone, and Investiture of Wind each once without expending spell slot. Using these spells in this manner, does not use your concentration, but the each spell only last for 1 minute. You regain the use of each spell after you finish a long rest.

I don't have much experience with the artificer in play, but I'll take a shot.

I don't see any real issues. It may be slightly underpowered compared with the other artificer subs. One thing of note, I would consider changing the first ability to have it either be a separate infusion, or be able to affect a weapon or piece of armor you've infused. The benefit is that a) you interact more with the base class and b) you benefit from applying this ability to a magic item that you've already attuned, rather than needing to attune to a new one. You could probably make this more powerful still. Compare this 3rd-level feature with those of the artillerist and battlesmith. This should be an ability that really changes the way you go about the game.

For your 5th-level feature, you don't need complicated language. "Whenever you deal acid, cold, etc... damage you can deal additional damage of this type equal to your Intelligence modifier".

For the 9th-level ability, I might make the resistance switch more frequent. Maybe you can change it as a bonus action a number of times per long rest, rather than just once. Again, the existing subs squeeze a bit more power out of this ability.

Thanks for looking it over, and I'm inclined to agree with you. I'm going to play around with this idea some more, but thinking of putting more emphasis on spellcasting ability of the class, not to the point that they can match full casters though. Also, yeah... I don't know what I was thinking with the wording for the level 5 feature, definitely going to simplify that. As for the level 9 feature, not sure if I want to be too often, but I'm probably going to change this to be about to changed on short or long rests. Not sure if I'd want the ability to change during combat, but I could try out your recommendation with it as a "once per short rest, you can use your bonus to..."