This is a combo that just happened once when I was yo-yoing without really thinking. I made this tutorial video to show you how to do it yourself.
Using your throw hand carefully is very important to making the tower. Once you can do this trick, I think you’ll find that the moment the slack falls into the tower is very satisfying. After you hit it, you can continue the combo into whatever you feel like! The continuation in the video is just an example that I came up with.
As you can see, I connected it with whips. By the way, the way of doing this whip is different from Iron Whip and Plastic Whip. People practicing those whips and having trouble getting them might try this one. It may be easier for you.