How does the Mythic skins level work?

[Psalms]

Can you level up a mythic skin by just playing in qp or rank?

Or does it need to be done by transactions with prisms and money?

[MBK]

You use prisms

[WhiteKnight]

You will need to get prism. Either from store or battle-pass. Use MS rewards to get OW coins and then get those bp.