Aetheric Armillary

This small glass orb is given to students of magic in order to help them understand the hand motions required to cast spells.

A spellcaster in possession of a Aetheric Armillary can use it as their spellcasting focus.

As a bonus action you can toss the Armillary into the air in front of you, causing it to light up and levitate. 

While active, the Armillary projects a spectral image of the solar system that can be manipulated to cast spells. While it is active you cannot make stealth checks, and it sheds bright light for 15 ft.

Any spell you cast through the Armillary while it is active gets a +1 to its DC. Once you cast a spell, whether it gains the bonus or not , the sphere drops, and becomes inactive.