Similar to damage per pip spells, damage per level spells deal a base amount of damage that accumulates based on your level. For example, a spell of this type's effect could be "deal 8 damage per level, or deal 4 damage per level to all". So by level 110, these spells would do 880 and 440 to all, so while they seem weak, the stronger you get, the more powerful these kinds of spells get. And since they get stronger with your level, they could have contributed use, where other spells become to weak to use. They would also have a set pip cost, so as you get higher in level, the pip to damage ratio benefits you more and more.
