Siege Magic

Prerequisite: The ability to cast a 3rd level spell. 

You gain 1 intelligence, charisma, or wisdom to a maximum of 20. 

You are now able to cast spells that are level 3 or higher as ritual spells. These spells must have an area of effect, and they cannot be cast at a higher level. Furthermore, these spells deal 1d6 siege damage to constructs and buildings per level of spell.