Enigma
When Gates appeared all over this parallel modern Earth, only a select few people obtained special abilities all of a sudden.
People believed they were the chosen ones, their only hope of surviving what seemed to be an inevitable apocalypse.
However, all the hype around them died quickly once humanity found out how to use an Enigma Stone.
After risking their lives to kill monsters with great difficulty, the Ability Users, who quickly took on the title of Heroes, always found strange stones inside.
They came in all sorts of irregular shapes, and although the stones themselves were in transparent gray, they possessed a multi-colored shimmer inside them.
They looked mesmerizing enough to beat even diamonds as jewelry, but times dictated that no one cared for such luxuries. Humanity immediately started researching every possible use they could have!