Void Bomb

A small blue orb of light descends from the sky to a point you can see. Upon reaching the ground, the orb expands into a swirling globelike vortex with a 20 ft radius, sucking everything in range toward the center of the sphere, with no exceptions. It uproots trees, breaks the ground and destroys rock and metal. Creatures must make a DC STR saving throw, or be sucked into the vortex, taking 8d8 void damage.  Successful saves remain on the ground and take half damage. Those captured by the orb can repeat the save on their next turn. On the next turn, the orb expands its radius by another 20 feet. Creatures must make a DEX save to keep out of the orb, or take 8d8 void damage. Creatures that start their turn within the orb on this second turn take an additional 8d8 void damage. The caster must maintain concentration on the spell for both turns. After the spell is complete, it leaves a crater in its area of effect that is considered rough terrain.

For each level above 5rd level, the orbs radius extends by 5ft for both the initial and secondary phase.