You create a portal to the Aether plane, a dimension that layers the material plane. While in the Aether you have resistance to all types of damage, and creatures can perceive you as a blue shimmering blur. You will have disadvantage on ranged attacks since the world around you is ever changing.  Every 5 ft traveled in the Aether counts as 10 ft in the material plane, and you can phase through solid objects at the cost of 15 ft of movement speed for every 5 ft phased. You cannot end your turn inside a solid object or entity. You must make a DC 12 constitution save at the beginning of each round. The spell ends if you fail at the save. On a success you are able to stay in the Aether, on a fail, you are snapped out of the plane forcibly and take 2d4 bludgeoning damage. If you are inside a solid object, you take 2d8 bludgeoning damage.