Battering Ram (破城槌), also known as Point Burst, a magic that was developed through PK research. This magic functions by rewriting the Eidos of the target object and applying a massive Weight Type Magic on a single point. When used against buildings, the target requirement is usually a wall or the ceiling, or at least a "single surface" that is separated from any pillars, and also required a colossal magic capacity as well as high interference strength. 
If simply destroying a building was the goal, it would be more efficient to use Move-Type Magic, and swing a hammer around. In comparison, "Battering Ram" is a highly demanding magic that, besides BS Magicians, is not something to be used nonchalantly.
If used against people in closed environments, the magic "Battering Ram" rates as A-rank in destructive power. This is on a completely different level than the danger encountered during Battle Board and is a blatant violation of the rules.