You propel yourself with a burst of fire and jump up to a point within range.  During this jump, you can hurdle over objects up to 50 feet high.  When you land, a wave of fire and thunder sweeps out from where your feet hit the ground.  Each creature in a 15-ft. sphere originating from the point where you land must make a Constitution saving throw.  On a failed save, a creature takes 3d8 fire damage plus 3d8 thunder damage.  On a successful save, a creature takes half as much damage.    

Also on a failed save, a creature is pushed back 10 feet and is stunned until the end of your next turn.  The creature also falls prone. 

If you make a melee attack immediately after casting this spell, the attack deals an extra 2d6 fire or thunder damage (your choice).  

You can also sacrifice either some horizontal or vertical distance to increase the distance jumped in the other plane.  For example, you can choose to only jump 20 feet forward to jump 70 feet high.   

At Higher Levels.  When you cast this spell using a 5th-level spell slot or higher, both the fire and thunder damage each increase by 1d8 for each spell slot level above 4th.  Additionally, you can jump an additional 10 feet (can be applied to either horizontal or vertical distance) for each spell slot level above 4th.