Warmup
Row 1k

Workout
Front Squat 10-10-10-10-10
At the end of your last set complete 1 round of max rep Wall Ball Shots in 1 minute.

Practice
Jumping rope-gain speed and control with your single unders.  This will better prepare you for double unders.  You do not need to rotate your entire arm to spin the rope.
If currently do double unders in singles, work on triples.
If you currently have a good double under, make it better.