Doom

You conjure magical energy in the form of a small red and black sphere. It floats upward and over the duration of the spell swells in size. It begins as a small emanation of energy within a 5 ft. cube. Each round, a new effect occurs until the end of the spell duration. These effects target all creatures within a 120 ft. range of the sphere.

1.  On the round the spell is cast, the energy from the sphere eliminates all ability to fly. Any creatures in 30 ft. radius of the sphere under the effects of a Levitation or Fly spell, or those levitating or flying by other means, have their ability to do so removed. If they are in mid-air, they fall to the ground, taking fall damage.
2. On the round after the spell is initially cast, the sphere begins to enlarge. It now fills a 10x10 ft. area. All creatures in range are dragged closer to the sphere at a rate of 10 feet per round. Each round, from this point onward, all creatures grounded by this spell must make a Constitution saving throw. On a failure, their movement is reduced to 0.
3. The sphere continues to grow larger. It now fills a 15x15 ft. area. All forms of magic being cast within the range of the sphere can only be used with a successful Constitution saving throw. On a failure, the spell is cast, but the magic is absorbed by the sphere.
4. The sphere continues to grow larger. It now fills a 20x20 ft. area. At this point, the sphere explodes, dealing 12d12 force damage to all targets within 20 ft. of the sphere. If any spells were absorbed by stage 3, and those spells would have dealt damage, the damage of those spells is added to the damage dealt in this stage.

(* A perfectly spherical, dark-red gem, encased within golden glass worth at least 200 gp.)