Chrono-Blast

A ripple  of energy emits from your palms. The attack does 1d8 damage. The target must roll a constitution saving throw. If the target fails, you may spend 1 bonus action to either have the target fall prone in slow motion or have its movement speed reduced by half for it's next turn. 

Starting at level 5, whenever the target fails it's Constitution Saving throw, you may spend 1 bonus action to have the target fall prone in slow motion and reduce its movement speed by half.

The damage is increased by 1d8 at 5th Level(2d8), 10 Level (3d8), and 15th Level (4d8).