Big Hat's Glorious Globe

A 10ft radius dome forms around you for the duration appearing like a glassy black globe before shimmering into invisibility. You can choose the interior of the globe including lighting, temperature, weather and decor. The Dome is completely invisible from the outside and can fit up to four medium or smaller creatures. Any creature or object can go through the globe, however elemental effects are repelled by its barrier.  

When creatures rest in this dome they gain 3d8 temporary hit points at the end of the rest as a faint trace of crystalline magic until they next rest or until the THP is depleted.  

When you cast this spell using a spell slot of 4th level or higher the damage increases by 1d6 for each slot level above 3rd