Unfold combination panel, then place +2 or above equipment into a slot, then click to decompose the equipment as the picture below shown:
After decomposing equipment, you will cost a certain amount of Gold but get some magic debrises. More magic debrises can be got when decomposing higher level equipment. Likewise, more magic debrises can be got when refining higher level equipment unsuccessfully. Magic debrises can be used to raise success rate of refining or exchange with mystic merchants for equipment.