I like these types of games where you don't need to hurry and you have time to just think. I played a little and picked out some ways of improvement :
1. Autobatler mechanic is very good, so if in this game idea of arena more developed it could've been more interesting. Maybe great boss in the end of countdown for 3 of your slaves or something like that.
2. In future think about step by step tutorials in your games, this game has a lot of text and tutorial looks huge against this background.
3. So like i say too much text, in future think about simplify something not important in text or make images for some buttons.
4. In the begining after reading tutorial i lost in the notification pannel, maybe some fade or somehow distinguish it from the background information makes it better for navigation (or maybe i lost cause it hard to find cancel button on this panel).
Anyways this game is nice, good job!