I just beat Ascension 8 with Regent, now on 9 with every character. Took like 30 tries.
Only reason I won, and it was a forgone conclusion when I got to the last boss (Queen), is because I had a Particle Wall (Gain 12 Block. Return this card to your Hand.), with Retain (from an Act 1 Event), AND held on to a Touch of Insanity (Choose a card in your Hand. It is free to play this combat.) from early in Act 1 all the way until the end just to do that. Drew the card first turn, it was beautiful. Unlimited block every turn, which was good because my attack kind of sucked.