Don't fall into the trap of calling counterfeit cards proxies because it helps normalize their use in the community and reinforces their acceptability, which is a bad thing for the game, its players, local game stores, and Wizards
So, if your commander is Priest of Ancient Lore and the signature equipment is Embercleave, your decks color identity is Boros
You can even eliminate players by pairing this with a card like Traumatize
Depending on context, these cards may be called prison pieces, hate cards/hatebears, sideboard cards, or, in some circles, stax cards after the ancient Smokestack-based deck which popularized not letting the other person play as a strategic archetype