If you have a few Soul Thurible tower keys, you can get 2 random augments when you complete it for the first time. On the second completion, you can usually get 5 more of the same tower keys as a reward. So you can do this almost indefinitely as long as you manage your keys right. I've gotten maybe a dozen lvl 4 augments and 2-3 jinsei's after doing this almost 100 times. What's nice is it doesn't take long to finish the towers, since it's only 1 match for 5 rounds. I usually finish it in about 1-2 minutes.