Diamond Dimension

Bending the threads of energy in time and space, you create a hectogon of mirror-like fractals in a 60-ft hemispherical dome centered around you. The interior surface of the dome sparkles and shimmers as if the creatures within are trapped in a diamond. The exterior of the dome reflects the environment around it giving the illusion of invisibility.

While in the dome, you and your allies have advantage on all saving throws and ability checks. Additionally, while concentrating on the spell, you can use your action to extend the crystalline structure of the dome to shape walls, platforms, ramps, stairs, or other similar constructs no larger than a 10-ft cube. These structures have the same properties as the wall of the dome.

You have control over what can pass through the wall of the dome. It is immune to all damage and can't be dispelled by dispel magic. A disintegrate spell destroys the wall instantly, however. The wall also extends into the Ethereal Plane, blocking ethereal travel through the wall.