You cause a spire of rock to burst out of the ground, floor, or another surface beneath your feet. The spire is as wide as your space, and lifting you, it can rise up to 20 feet in height. When the spire appears, a creature within 5 feet of you must succeed on a Dexterity saving throw or fall prone. As a bonus action on your turn, you can cause the spire to rise or descend up to 20 feet to a maximum height of 40 feet. If you move off of the spire, it immediately collapses back into the ground. When the spire disappears, it leaves the surface from which it sprang unharmed. You can create a new spire as a bonus action for the duration of the spell.