Some ideas: raiding, seiging, spell AI and more..

[Cheezeninja]

It seems to me that almost every time im using crumble, im doing so because there's a large number of defenders inside the castle keeping me from beating down the walls. When this is the case all that seems to happen is that crumble beats down the walls but then the defender vs besieger check happens afterwards and I get the message saying the defenders are repairing the wall faster than I can beat it down and I dont actually get a chance to storm the castle. While some damage is implied in the spell description I have never seen any statistics on it, or any noticable damage when I cast it.