I find manual battles a bit tedious in this latest instalment of Age of Wonders. The completely new skillsets, abilities and races are a little overwhelming, so I prefer to do automatic battles. The good news is, you can still do this and get the achievement. Simply engage in a manual battle and toggle auto-combat on (the icon with the two swords crossed in the bottom right of the screen). Also, be sure to activate 3 x playback speed which can be done at the bottom of the screen. Just do this whenever there is a small battle that will be over quickly 100 times as your playing and the achievement will be yours in no time.