Is this really so bad? It takes away your control of choosing who will engage an enemy but at the same time it removes that enemy from the staging area during questing, meaning you get to skip dealing with their threat level. The enemy would have engaged that turn anyway.
I'm hoping they have some cards with specific Forced effects after an Ambush is successful, such as bonus attack power until the end of the round or something. That would be pretty cool.
I'll have to wait and see how it all plays out to say for sure just how devastating it can be though. What does everyone think about Ambush?
