They are really not a big help they can kill of some troops.And there numbers says it all.But the smart thing they did to this was not make them count as bp,(which is a bad thing to myself)if so there would be alot of processions going on.In grepolis, there defense is as worse as it can be and there I bet they can prorbaly kill of a small group of swords, though.They mostly have a small dent to a player that is getting attacked.