Ok, this is going to be complicated to explain but it is a somewhat game breaking bug and would be worth while to fix. In a recent event where I Lava'd a cliff tile, froze it again to turn it into rock to make a mine entrance the actual cave tile underneath it turned into a lava tile which had to be froze again to get rid of. Now, the actual lava tile underground had no effects of being lava, it didn't hurt nor have I seen it spread underground, so why does it exist? o.O All I could see myself doing now was making a ridiculous safe mine where on top of having reinforced tiles I could also have lava tiles so that if an enemy raids they would have to bring someone on Path of Power to get in. OP right? I am yet to do some further science on it, to check if when it does spread the tile it spreads onto turns into lava underneath as well? And If you cant erupt a lava tile underground how come you can freeze one?