Spell Fusion and Spell Combos.
I think there should be a new item, like a spell fusion chamber. So you could have like a healing spell and a rage spell and you could have a rage heal! Or rage freeze! Or a combination of all three. However only make it so you can combine three spells at most. Another idea is you can also make it so when you use a certain combination of spells together, it causes some sort if reaction. Example: Put one rage spell down and then three lightning spells in the same area, and it creates some sort of super energized lightning that lasts longer and does more damage.