In Terraria, how much space is required for a fire imp to spawn/teleport? So far, I've kept my hellstone mine restrited to either 3 tiles high or 2 tiles wide, and I haven't had any trouble until I attempt to mine a large patch of hellstone. So what is the minimum required space for an imp? It must be more than 2x3.
Fire Imps seem to require a target space of 4 blocks high by 3 blocks wide to teleport into a location.
From the Terraria Wiki
Just be sure to fill in some of the hellstone you mine to keep the imps from spawning.