Necklace of Fireballs

As an action, detach a bead and throw it up to 60 feet away. It detonates as a 3rd-level fireball spell (DC 15). You can hurl both beads, or the necklace, as 1 action. +1 level per bead.
Fireball
Each creature in a 20 ft radius sphere makes a
Dex save, taking 8d6 fire damage on failure, half
on success. The fire spreads around corners. It ignites flammable objects not worn or carried. At 4th level or higher, +1d6 per level over 3rd.