Conjure Pebble

Conjure a pebble in the worst possible location for an enemy to step on. The creature must make a Dexterity Saving Throw or fall prone. If the creature succeeds the save then the pebble remains in that space until the end of the round. If any other creature attempts to walk through the space before the pebble vanishes they will also need to roll. Upon a creature failing the Saving Throw the pebble will disappear. 

This spell’s duration increases to 1 minute when you reach 5th level, 10 minutes at 11th level, and a hour at 17th level.