The compound system is so fantastic that you can exchange excessive equipments for any other equipments of the same set you need. And the new equipment generated is unbound and tradeable! It's such a great system! Let's see how the system works.
Take Breastplate as an example.
Target: an epic Phoenix Breastplate
Step 1: Click equipment B4 on the right of the interfaces with the left button,and then add it to the middle of the furnace (target equipment). Say, let's add an interior Breastplate of Valiancy (the equipment added is unlimited but it must be blue.)
Step 2: add 3 peripheral equipments of Set A (target set). Let's add 3 epic Phoenix spears (as long as they're of the same set).