KI updated some spell card symbols to be more "clear" in meaning. I was pretty baffled by it at first too because it makes way less sense than the old symbol but apparently that symbol on cards like deer knight means that it affects all enemies. Shrug.
i have noticed that too but i never knew what it was. It shows up on my ice spells like the blizzard. It might mean spells that attack all enemies or smth but im still not sure...
If you click on the Help tab of your spell book, go to the third tab over which is Interface, and look at page 5 it will explain the new spell card symbols.