Welcome. In this guide, I will explain how to make +13 items.
You will need:
4 +9 Item[more success rate if it got nice option]
4 Chaos Jewels
10 Bless and 10 Soul
So First put the +9 item in the chaos machine, and add the 1 chaos and 1 bless and 1 soul and press Mix, hopefully it works out because the rate of succeeding isn't very high and keeps lowering as you go higher and higher +
then repeat the process, this time add the +9 Item with 1 chaos, and 2 bless and 2 soul and press Mix
Same thing here with 3 bless and 3 soul, press mix
and finally(if you make it this far) add 4 bless and 4 soul, to have a +13 Item : D
Happy try and Good Luck for it!!