Bolt of wind

You stretch your arm towards a target and speak a verbal command. A bolt of strong, dense wind swirls around your hand and fires through your palm in a straight line. The bolt is 5 feet in diameter. The target of the spell must make a STR save or take 2d8 + 2d4 force damage and is knocked prone. For every level above second that the spell is cast, it will deal an extra 1d8 + 2d4 of damage.