Sphere of Annihilation

From Dungeon Master's Guide, page 201. Found on Magic Item Table I.

Description
Wondrous item, legendary.

This 2-foot-diameter black sphere is a hole in the multiverse, hovering in space and stabilized by a magical field surrounding it.

The sphere obliterates all matter it passes through and all matter that passes through it. Artifacts are the exception. Unless an artifact is susceptible to damage from a Sphere of Annihilation, it passes through the sphere unscathed. Anything else that touches the sphere but isn't wholly engulfed and obliterated by it takes 4d10 force damage.

The sphere is stationary until someone controls it. If you are within 60 feet of an uncontrolled sphere, you can use an action to make a DC 25 Intelligence (Arcana) check. On a success, the sphere levitates in one direction of your choice, up to a number of feet equal to 5 x your Intelligence modifier (minimum 5 feet). On a failure, the sphere moves 10 feet toward you. A creature whose space the sphere enters must succeed on a DC 13 Dexterity saving throw or be touched by it, taking 4d10 force damage.

If you attempt to control a sphere that is under another creature's control, you make an Intelligence (Arcana) check contested by the other creature's Intelligence (Arcana) check. The winner of the contest gains control of the sphere and can levitate it as normal.

If the sphere comes into contact with a planar portal, such as that created by the Gate spell, or an extradimensional space, such as that within a Portable Hole, the DM determines randomly what happens, using the following table.