Cube of safety

You make an area within range magically secure. The area is a cube that can be as small as 5 feet to as large as 50 feet on each side. The spell lasts for the duration or until you use an action to dismiss it.

When cast nothing can pass through this barrier without the casters permission.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, you can increase the duration of the cube by 2 hours for each slot level beyond 1st.