Wo Long: Fallen Dynasty

Plays like it reads- play through ten battlefields with a companion (NPC or another player-doesn't matter). You can use Tiger Seals at Battle Flags to summon NPCs like Zhao Yun or Guan Yu, random players, or you can invite friends to play, all through the Online Lobby and Reinforcements tabs.

You can do the same battlefield multiple times and it will count, but this does not include replaying the battlefield in your world. For example I played through Two Chivalrous Heroes with a buddy in my world and afterwards he summoned me for his Two Chivalrous Heroes and achievement progress went up both times.

I do not know if sub battlefields count for this, but I unlocked the achievement before the end of Part 4 so either way it should come easily with time.

Hope this helps