Heya, I just got an idea for the Flesh to Stone spell.
When the spell is cast, this powerful curse starts to turn the victim into stone slowly, starting from his feet and going up. The victim is immobilised (an entangle effect without that yellow wine-animation) without a save (since his feet are petrified and stucked to the ground) and starts to slowly convert into stone. It takes an entire round for the spell to go up and reach the victim's heart and kill him, turning it to stone completely.
During this round, the victim must make a save vs spells (at -4 penalty, or whatever is appro