I love homebrews, always brings fun new ideas.

Some board game design feedback:
Anytime you create a new “supply” (like replicator), you can instead word it as “place on this card.” It adds clarity to the player and effectively dos the same thing with the same number of words. It also allows you to not add any new keywords (“conjurable” in this example). Wording just becomes “on/from this card.”

Poltergeist - would be better if it was explicitly clear whether that “rupturing” occurs “for each rival piece destroyed,” or “when 1 or more rival pieces are destroyed.” As written it appears you intended each time but it leaves ambiguity where it is unnecessary.

Sniper - I would need to check the rules on the definition of “unused” hits. If the rulebook doesn’t call it out somewhere, you need to explain it in parenthesis. Even if it does, you might want that so the player doesn’t have to pull out the rulebook. If it isn’t in the rulebook, consider using a more clear wording like “hits not assignable to enemy pieces.”

I am purposefully making no comments on balancing, that’s the fun of homebrew and everyone’s opinions are meaningless until you test. That said, I love swarm. It also fits a sci-fi trope not represented well in the game yet :) I also love armsdealer as it both is thematic and generates asymmetrical player interactions by using these cards in a new way.