The only strategy that works for me is a rerolling based deck and hope to get all perfects to beat the last boss. Every upgrade I choose rerolls (if there's no reroll then I choose heal) and the strat is to stay at or below 7 and reroll for 13
Yeah after a few more tries I beat the boss. And as a reward I had to imagine the ending, lol.
I think I did it with a combination of attack, defense and heal. I tried bones but they're unreliable.
The only strategy that works for me is a rerolling based deck and hope to get all perfects to beat the last boss. Every upgrade I choose rerolls (if there's no reroll then I choose heal) and the strat is to stay at or below 7 and reroll for 13