It would be helpful to have an upgrade option in the deck editor so that if you have an extra copy of a card and want to improve the existing one in the deck, that you can do so, instead of enter editor, remove card, save deck, enter lab, choose cards, upgrade, leave lab, re-enter editor, restack in deck, leave editor. Too many steps.
And now on level 32, I have >1400 health and >10K gold. I can't kill him even if I try. And this is the first run through with him. Played vampire once to unlock, then this run. I like the update, but this character is way overpowered. The previous version at least gave you a little challenge.
Shift + click will let you disable the warning and step onto dangerous terrain.