A guide on how to fight ambush battles (useful tips) in Hero by Chance.
How to Fight Ambush Battles (Useful Tips)
Be sure to click on a unit with a lower level than yours. Avoid clicking on units with higher or the same levels (by 屠龍).
After experimenting, I noticed that you can just click on all the highest value enemy units and still clear the mission. If you have equal value as the enemy (eg. start with 3 and click on 3) it still count as your win, after the first one you will always be higher than the enemy’s highest, and just speed your way through (by Autonomy).