Things you need:
Basic ATK Core
[NEW EDITED LOADOUT] Infinite, Liberation, Surge, Master, Blade Edge
Use MC ult or Carole to knock away enemies to proc Raiden's QTE, and then hold attack button to spam her KE ability.
Timido MC Mei is the best combo from my testing. Timido's ult and freeze status can trigger MC's QTE a lot to help the ignite status. Ignited enemies also trigger Mei's QTE. Don't overlook how smooth this team comp is. Try it out!