Elminster's Effulgent Spheres

Source: Forgotten Realms Heroes of the Forgotten

6th Level Evocation (Druid, Sorcerer, Wizard)

Casting Time: Action Range: Self Components: V, S, M (an opal worth at least 50 gp) Duration: 1 hour

Six chromatic spheres orbit you for the duration. While the spheres are present, you can expend spheres to create the following effects: Absorb Energy. When you take Acid, Cold, Fire, Lightning, or Thunder damage, you can take a Reaction to expend one sphere and give yourself Resistance to the triggering damage type until the start of your next turn. Energy Blast. As a Bonus Action, you send one sphere hurtling toward a target within 120 feet of yourself. Make a ranged spell attack. On a hit, the target takes 3d6 Acid, Cold, Fire, Lightning, or Thunder damage (your choice). Regardless of whether you hit, the sphere is expended. The spell ends early if you have no more spheres remaining. Using a Higher-Level Spell Slot.
The number of spheres increases by 1 for every spell slot level above 6.