2,200 NX (1)
22,000 NX (11)
Black Cubes are used to reset revealed Potential stats on equipment items. They also offer the chance to decide whether or not to apply the new Potential to your item. Items with hidden Potential on them are most commonly obtained as drops from monsters, from event rewards or coin shops, if you transform them yourself using a Potential Scroll or Tim's Secret Lab, or if items with Potential are fused. Each Black Cube can only be used once. This item can be found in the Equipment Modifications > Miracle Cubes category in the Cash Shop.
Here's how to use a Black Cube:
As a bonus, you will receive a Black Cube Fragment in the Use tab of your item inventory. After you collect 5 of these, double-click them to obtain an Advanced Equip Enhancement Scroll, or combine 15 for a Perfect Awakening Stamp, or combine 30 to earn a Special Bonus Potential Scroll.