Hi everyone!

I have one question on The Three Trials scenario in solo play. Let 's say, I'm on third quest stage 2A - The Trials of Strength. In combat phase I kill guardian enemy right now, obtain key objective and go on quest stage 3A. Here when revealed effect orders reveal each guardian enemy in victory display, adding them to the staging area. Of course guardian enemies engages me and my question is: Can I still attack them ? I'm still in combat phase.

Yes, you can. As you say, you are still in the part of the combat phase where you get to declare attacks. If there is anything to attack and you have anyone who can attack, feel free.

Also, since the guardian left play, he is kind of a new copy of himself, from the game perspective. That means you can attack him again, even if you attacked the old copy this phase.