I've played this game for quite some time now (this is my second account), and over the years I've always seen the same casting animations for all the schools. The animations are fine, but after seeing the casting animation for Shadow spells, I was blown away by how much more detail can there can actually be. So, I think it would be really cool if each school (including Astral schools) got an updated casting animation with greater detail.
Another thought I've had is adding a feature to the game that allows players to change how they stand in the battle circle and how their characters physically draw the casting animations. For example, depending on what kind of wand a wizard has, their drawing animation will be different from other wizards with different wands; I think it would be a great addition to the game to allow wizards the option to choose different drawing animations, or how they stand in the battle circle.