The Sprung Cascade is a unique
four ball trick that is essentially the three ball Cascade with a fourth
ball being passed between hands with every throw. The pattern can also be
thought of as a Box with the vertical throws being switched to Cascade
throws. The Sprung Cascade is an enjoyable yet difficult pattern to juggle,
and looks good to spectators.
To learn the Sprung Cascade, it is best to start with an adaptation of the three ball Box. Juggle a standard Box, but then make one of the vertical throws from your dominant hand a high Cascade throw instead. While that ball is in the air, make a second high Cascade throw with your non-dominant hand, passing the remaining ball in your dominant hand to your non-dominant hand, as if juggling the normal Box. Then, as the first ball begin to come back down toward your non-dominant hand, pass the third ball back to your dominant hand, and then catch the first ball. As the second ball is approaching your dominant hand, resume juggling the standard Box by making a vertical throw with your non-dominant hand paired with a horizontal pass from your dominant hand.
Practice this extensively. Once you have it mastered, you are ready to add in the fourth ball. Start with two balls in each hand, and then make one high Cascade throw from each hand, starting with your dominant hand. As the first ball approaches your non-dominant hand, make a third Cascade throw from your dominant hand and pair it with a horizontal pass from your non-dominant hand, clearing space in your non-dominant hand to catch the first Cascade throw. As the second Cascade throw approaches your dominant hand, make a fourth Cascade throw from your non-dominant hand, and then make a horizontal pass from your dominant hand, clearing space to catch the second Cascade throw. Then catch all the balls.
This step may take some time to master. It might help to work on just doing the first Cascade/horizontal pass combination, in order to get used to the throws. Only after the first one is mastered should you then try chaining two together.
Once you have the above step mastered, you need only continue making Cascade/horizontal pass combinations and you will be juggling the full Sprung Cascade. While practicing, you should eventually start to get into a rhythm, which will make the trick much easier.