Hi,
I am experienced nodejs developer with over 5 years of experience.
I can create backend api and help you connect and test it to mobile app.
Will create gashapon system player/boss/enemy, matchmaking, item forging and pvp leaderboard.
Aslo will create admin panel.
Also, I can offer to write servers in golang, and have really nice traffic optimization, since golang is more realible for this stuff that you are asking.
If interested, contact me, would like to know in detail about this project.
BTW, since this is bigger project, I will offer a guarantee to this code. Meaning if there is bugs caused by my code in production, will fix it free of charge.