Dreamscape

Creates huge opaque orb centered around the caster. Creatures can make an intelligence saving throw when the bubble goes up or when a creature enters the bubble. On a success, it sees the bubble and its contents as a hollow illusion. Each turn as a free action, the caster can alter the contents of the sphere. Affected creatures have disadvantage on attacks and saving throws while inside. 

The bubble is opaque and has an outer membrane that can be passed through. It has an AC of 10 and hit points equal to 10 x the level of the caster.