Astral magic is a useful tool, anyone past DS knows that much, and while Moon seems to be fading from the game, and Sun has covered almost everything it can, Star's potential has barely been touched upon. Sun can increase attacks, heals, charms, wards, and pretty much every relevant card. Star can increase your personal damage, defence, critical, block, accuracy, and pretty much every stat in-game. But while Sun stays in your hand only, Star could easily be augmented to affect allies and opponents. Here's some ideas:
Weaken, 1 pip, +15% to incoming damage to target for 4 rounds. Reduce, 1 pip, -15% to outgoing damage to target for 4 rounds. Fallible, 1 pip, -15% to accuracy and pierce to target for 4 rounds. Forgiveness, 1 pip, -20% to critical chance to target for 4 rounds. Refusal, 1 pip, Lose 1 pip from outgoing spells ranked 4+ to target for 4 rounds (Pip refusal next turn).
Uncertainty, 1 pip, -90% stun resist & -20% critical block to target for 4 rounds. Placate, 1 pip, -40% outgoing & -30% incoming damage to target for 4 rounds. Worsen, 1 pip, -20% outgoing to target for 4 rounds.
Dampening Field, 1 pip, -25% outgoing damage, -5% accuracy, and -10% incoming damage to target for 4 rounds (Et cetera for other schools).
The level 110+ progressions could cost 2 pips instead. This could give way to spammable Balance strategies (offensive aura, Extraordinary Supernova, rinse and repeat), but in that case they could be made no PvP, and enhance the PvE experience. They're easily countered by a positive aura from the target, but it adds new strategies and increases the need for auras in decks, bringing Star back, so it doesn't suffer the way Moon did (Moon Mastery Amulet and shift spells are viable, just saying).
Of course, that's just offensive auras, the existing auras could be changed to target an ally rather than just self, and AoE positive and negative auras are also within the realm of possibility. But I personally think Star has a lot more to give to the players of this game.