It's because we don't have everything from China. If you want to know when we get skill breaks for main characters, go and check out updates on Wednesdays to see when it will be added.

hi OP, lightning sharkbomb (and other main character mysteries that combine 2 elements) are part of a system in CN tbat hasn't been implemented in our version. lightning sharkbomb is therefore currently unavailable at the moment for us!

Will be added here in what they'll call 6.0

It's a skillbreaktrough for main characters.

Does main breakthrough need main frags too just like the other breakthroughs?

From what I understand, its a completely different system.

I think you have to do certain things in Arena or something

as far as i know it works like summon cultivation, where you have to unlock circles for various stages. you can unlock these circles by completing tasks (winning at arena, completing survival trial, doing ranked battle). Main character fragment are not needed.

of course keep in mind that these requirements are subject to change at oasis' discretion.