Specifically, I want to trigger Overpower on enemy Dodge. What conditions do I need to add in the Fighter Creator to make it this work?

I havent tried this, but if you put it at the top of your spells / rotation. How does that work?

I thought the bot was able to detect if a spell was available (That might be one of the options in the top right)

It won't work, because the spell is only usable in battle stance, not zerker stance. 
Droidz needs to fix Lua events with arguments for older WoW versions.

I tried making it #1 (or top most) priority and had no luck. I just need to make it work though because my Arms warrior does WAAAAY more damage when he uses Overpower. Why does battle stance matter? I only use the one stance, battle, right now while I'm leveling at 22+. You are correct, it only works in that one stance.

 

Just add it to your spell list with the condition "Is Spell Usable".

 

 

It works. It works so well in fact that the Overpower is instant after dodge. Sometimes Overpower damage comes across on log before the dodge pops up lol

I have mine set

Overpower when 5 Rage is reached. Thats all I had to do. As soon as Overpower becomes available and he has 5 rage, he uses it. Its the only condition I have set for my Overpower and it works flawlessly.