Like the other's reply here, I also had a series of trainings on combinations from simple 3 to complex like 8 to ten arts but first about the "Circle of Death" thing it should be called RANDORI coz thats the proper name and its performed with variants of 3 ukes to as much as the nage can muster.
Now back to the topic
simple combinations may start from either katate dori or munetsuki, the arts may vary from nikyo then ikyo, move to sankyo then a nage can be applied either reversed (otoshi) or forward like a zempo nage throw.
If you have enough time you may experiment on combinations just remember the possible art you can apply on your current body position.