This crossed my mind. I know summoned stones are *not* figures, are *not* affected by OL cards, monster abilities, and hero abilities, and I *think* they don't treat heroes as friendly figures. (Not sure on that.)
I am not disputing the intent of Terracall at all. But if stones don't treat monsters as enemy figures, by strict RAI I don't think they can actually attack anything using Terracall, since the target space has to have an enemy figure in it.
Of course, Molten Fury and Earthen Anguish are fine because the stone isn't attacking.
Weird!