Dive bomber

You dive out of the sky, charging towards the enemy.  When you move at least 10ft in a straight line towards the target you get +5 melee weapon damage, for each additional 10ft you move, you do an additional +5 damage. On a hit make a CON save dc = additional damage dealt. On a failed save take 1/2 this additional damage an a success you take nothing. 

Must be able to fly and be wielding a melee weapon.