I want to say when it comes to mass combat enhancements like the soul cannon, before you really decide what they do, decide how we would handle mass combat.  I feel like in an army besieging us scenario we wouldn't be using it as written.<br/><br/>Though now that I think about it, we usually use the point objective system. The cannon could easily create a environmental hazard for enemies at one of the objectives during the battle there (every other round they save or take damage from it), or it could be used to slow down enemy point acquisition at another objective.  I guess if we are using that system leaving it as written is fine and we can adhoc it's use in an actual mass combat.