I had considered this before, but I think it would make more sense to have only one or two special enemies do that rather than any of them with smoke grenades, as smoke does restrict visibility quite a lot. Another issue right now is also keeping it optimized, as the smoke clouds are slow to render due to their sprite sizes. I can't really optimize them any further as the game engine just struggles with rendering lots of massive images at once, but some small use might be possible.