Board Thread:Questions and Answers/@comment-34514657-20180303003911/@comment-32271305-20180303012138

I still remember when the game didn't have any Hidden Potential system, and cards worked just fine. As long as they have a Passive Skill, Link Skills, and all that stuff, they can be used regardless of dupes.

Dupes can certainly increase damage output, but if a card is good, it will be good even without dupes.