Volcanic Cannonball

Through a bursting crack in the ground, you compress an orb of molten scalding rocks.
It has a radius of 5 ft/1.5 m.

You throw it in a line as long as your visual range.
The ground it flies across is also damaged, burnt or melt, depending on the matter.
It is a solid, sturdy sphere, so it doesn't go off at the first obstacle.

Once it connects to the target, it continuously pushes against it.
For each round, 1d8 bludgeoning & 1d8 fire damage.
The medium-fast rotation makes it hard to catch or immobilize.
If it is disrupted before the 5th round, it will explode with 2d6 fire damage in a 9 ft/3 m radius.