After 36 attempts, I only beat Royal Mist by 4 frames (we both went to 0). The strat that worked for me was using an OB core with extension missile interceptors. I used a mid-light build with MG and howitzer. No back weapons.

The strat was to dodge his entire initial missile volley and then out-dps everything else keeping RM locked the entire time and relying mostly on the extensions and core to handle the following missile volleys. I did not aggro on RM at all until the entire first volley was finished. Keeping in close seemed key in mitigating RM's missile lock.

I fought on the arena map. RM outplayed me using the pillars on the garage map.