Hi there, i've put some thought into this idea. I would like to introduce: "Void" spells!
When you mix moon and shadow, you get shadow forms. But what if you mix star and shadow? That's when you get Void!
Void is like star magic, except you place it on the enemy, and it provides debuffs!
Here's an example of one:
Hallucination: (requires 1 shadow pip, 0 normal pips) -15% accuracy, -5% damage. Chance to stun enemy for 1 round, lasts 2 rounds
Basically, placing a void spell on an enemy creates a second aura around them. This means the victim can still have astral spells active, but it will collide with void magic and make it weaker.