Hi, I'm just going to rattle off a few ideas for new spells,
Petrify (or maybe just a quest where a high level cleric can "cure" it, maybe off a new companion, or possibly a non combat spell to store prisoners)
A summon-able stack of "Holy Lances" for clerics, just re-skinned golden light javelins basically (i know the spiritual hammer, fills this niche, but maybe these could be a more viable weapon for sieges? increasing the projectile speed to bow speeds?)
I would **** my pants if meteor swarm was a possibility, not sure if it's do-able, but if so i would love you forever.
Some form of a prismatic spell, (spray, or orb etc.) effects such as Petrify (fingers crossed), knock outs, blindness, charm etc. You know, a lot of the effects you already have implemented
Earthquake, could just use blunt damage and knock down, like a horse charge.
A temporary physical wall spell, (ice wall, stone wall etc.) could be used to seal siege points or protect archers/mages
A teleport, i.e. you just teleport to thrown location. maybe increase fall damage to require precise aiming/nerf overuse
Ice spells would be cool (no pun intended)