Opus of Elemental Substance
9-level Evocation
A thin flash of energy streaks into the sky from your raised hand. Moments later, an enormous sphere of lightning crashes to the ground at a point you can see. Each creature within a 20-foot radius 1,000-foot-tall cylinder where the sphere falls must make a Constitution saving throw. The sphere spreads around corners and passes through spaces as small as one inch.
Lightning arcs between each creature caught in the area of this spell. On a failed save, a creature takes 8d8 lightning damage for each creature in the area (to a maximum of 48d8). On a successful save, a creature takes half the damage.
Creatures wearing metal armor or comprised mostly of metal have disadvantage on the saving throw.