With orbital cannons/heavy artilery/weapons of science.
Using a death star (An onscreen feat) to destroy the planet'll do.
Destroy the ground underwhich the spell infected area covers, and the shield will be a non issue as everything above wthat point would be sent into orbit.
Still 'til that spell is scientifically explained, you most definitely cant be sure that heavy blaster fire wont annihilate it.
Simple tricks are no substitute for a good blaster at your side.