Unrefined Aether Filter

Unrefined Aether-Filter Wondrous Item, Rare (Requires Attunement by an Artificer) A heavy, palm-sized cylinder crafted from tarnished celestial brass mesh and capped on both ends with softly humming, raw cerulean crystals. It was gifted to you by the eccentric traveling merchant Alden Trance (under heavy, invisible protest from his unseen business partner). Arcane Integration: You can use a tinker's tools to attach this filter to a spellcasting focus or arcane firearm during a short or long rest. Elemental Inversion (1/Day): When you cast an Artificer spell that deals Fire, Cold, or Lightning damage, you can choose to route the magical energy through the filter. The spell's damage type for that casting completely shifts to Force damage instead, allowing you to bypass standard elemental resistances and immunities.

This rare item is a component originally designed and crafted either by some forgotten genius artificer, or by some crazed person operating in back-allies, Alden can't recall which. But this component can be combined with a spell focus or attached to the barrel of an arcane rifle to convert elemental magic into force damage. Alden has been trying to see if he can get a patent for it but has been unsuccessful thus far, maybe you will have more luck?...

Arcane Integration: You can use a tinker's tools to attach this filter to a spellcasting focus or arcane firearm during a short or long rest.
Elemental Inversion (1/Day): When you cast an Artificer spell that deals Fire, Cold, or Lightning damage, you can choose to route the magical energy through the filter. The spell's damage type for that casting completely shifts to Force damage instead, allowing you to bypass standard elemental resistances and immunities.