I'm most of the way through story mode now. As of my last post, I had four bosses left to beat, and in the previous five hours I've beaten three of them. My conclusion, based on these experiences, is that advancement in Hand of Fate is largely down to luck. Which isn't to say that there's no skill involved, but simply that a favorable distribution of cards require a lot less skill than an unfavorable one. For example, the first of the three bosses (and therefor, presumably, the easiest) took me three hours to beat. The other two took about an hour each. I wasn't really doing anything particularly different on my first run, it was simply a matter of drawing an effective combination of equipment while avoiding having too many unfavorable cards active at once.
It's not a mechanic I'm thrilled about. I play a lot of Magic: The Gathering, and knowing, if only in a rough way, the statistical composition of your deck is an important skill, but it's actually my least favorite part of the game. Managing chance simply never felt as satisfying as elegant design. It's doubly a problem here because you don't really have a lot of room to design your deck. Ideally, you want to select encounters with good risk to reward ratios, and equipment that will complement your playstyle, but usually the first time you defeat an encounter card, it grants you a token that unlocks more cards, so you want to heavily favor the new ones, and you don't get multiples of your best equipment cards, so it's impossible to weight your deck towards a particular gear loadout. It makes the chance element feel very arbitrary.
However, I shouldn't complain, because I'm winning. The only opponent I have left to face is the Dealer himself. Once he's out of the way, I'll be done with story mode (though I still have no clear idea about the nature of the in-universe game) and be able to focus on endless mode, which I suspect to be the real meat of the game. I imagine that if there is no definite end-point to your dungeon delve, then your inevitable death from a run of bad luck won't seem nearly so cruel.