originally you can't equip same 2 acc at one character.. this glitch allow you to equip 2 skill ring IV.
the step as seen in this video :
- Equip everyone (6 playable character) with Skill Ring IV
- Let Adol equip one at 2nd slot instead
- Make another Skill Ring IV, then press confirm button.
- That's it, Adol have 2 Skill Ring IV equiped, each gives -50% skill cost means he got -100% skill cost which make all his skill cost = 0
**Glitched fixed in US ver.