Debbie's Spontaneous Stairs

You conjure a set of stairs that opens up beneath 1 target within range. The staircase is 10ft. steep and the target must make a Dexterity saving throw. On a failed save, the target takes 1d6 falling (bludgeoning) damage. On a success, the target steadies themselves at the top of the stairs. 

The staircase remains in the space for 1 minute. 

Using a Higher-Level Spell Slot. The staircase becomes 10 ft steeper and damage increases by 1d6 for each spell slot level above 1.