Death's Doorway

You touch a doorway or window, and picture another doorway/window leading to a destination you've visited before. When you open the door, you and up to six creatures you designate can enter the door and teleport to the destination, and the door can be used to teleport to the location for the next minute. Inside the door/window, there appears to be a wide field full of ash, with ash falling from the sky. This illusory landscape disappears when the spell ends. 

If a creature you don't designate willingly enters the doorway, they must make a Constitution save. On a failure, they take 3d8 necrotic damage and gain a level of exhaustion. On a success, the creature takes half as much necrotic damage and no levels of exhaustion. A creature can only the doorway willingly, and is ejected back into a space within 5 feet if it enters the doorway unwillingly.