Plasma Lamp

The lamp glows, but the housing check does not count it as lighting. Put one in a room as the only light source and the room comes back invalid with no obvious reason why, which is a frustrating half hour if you do not know the rule. Keep a torch or a candle tucked behind furniture and the lamp stays purely for looks.

As decor it fills a gap. The animated filaments and the cold blue tint read as tech or laboratory in a way none of the lanterns manage, so it fits arcade rooms, sci fi bases and anything built out of metal. Real plasma globes work off a charged electrode in a sphere of thin gas, which is why the arcs branch the way they do.