Arbor's Tiny Dome

Roots sprout from the ground in a 10-foot-radius dome shape and cover you and up to nine Medium or smaller creatures in the area. The spell fails if there is a creature larger than Medium or more than nine creatures in the radius.  

Until the spell ends you can shape the insides of the dome by shaping the roots. You can create various shapes like a table, a bed, a closet and alike. Also, until the spell ends, you can make the inside be dimly lit or dark. The dome's atmosphere is always comfortable and dry, no matter the outside weather.   
The dome is immobile. Roots are magical, and if damaged will rapidly regrow. They also are very resistant to the elements, like fire. They are not indestructible however (high enough damage or Disintegrate spell can destroy it). 

Creatures and objects in the dome's area when you cast the spell can move inside and outside of the dome by willing an area of roots to open. 

If you add 20g worth of diamond dust when casting the spell, when the spell end, creatures that spent at least 4 hours in the dome and are no further away than 100 ft. from it, will gain Temporary Hit Points equal to your Wisdom modifier. The benefit last for 24 hours. 

At Higher Levels: If 20g worth of diamond dust is added, creatures will gain an extra 1d4 Temporary Hit Points for each spell slot level above 3rd.