Chance Missile

You create one glowing dart of magical force that moves sporadically towards a target within range. Make a ranged spell attack against the target. On a hit, the dart deals 2d4 force damage to its target. If you roll the same number on both d4s, the damage is doubled. 

On a critical hit, if you roll 3 of the same value, the sum of those values is tripled. If you roll 4 of the same value, the sum of those values is quadrupled. 

The spell creates more than one dart when you reach higher levels: two darts at 5th level, three darts at 11th level, and four darts at 17th level. You can direct the darts at the same target or at different ones. Make a separate attack roll for each dart.