Blazing Wheel

A flaming wheel rolls in front of you, it burns whoever it strikes. it moves 20 ft per second and can ride walls to reach its target, once hit the wheel explodes in a radius hitting anyone inside (5 ft) dealing 3d6 points of fire damage, a successful dexterity save will half the damage or on a failed save will be knocked prone. The flame with flutter out if it reaches maximum range. 

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.