I've unlocked two Legendary Jokers and I'm almost positive I got the second one from an Arcana Pack.
Meanwhile, I've gotten a win so far with every deck up through Nebula. It's been very tough going, though. I feel like 95% of my runs die by Ante 3 because I can't find a single playable Joker, or because I find a good starting Joker or two and then never find any way to support them. Like earlier tonight, I managed to start out with two Barons, and then not only was I unable to find a way to duplicate kings, I never even saw another king in my hand again.
I really am trying to stay open to new strategies and combinations that I haven't tried before, but I feel like I still have the most success with either flush-based decks or by duplicating cards. The run I won tonight ended up built around the Flush Five after I was able to duplicate something like 25 mult-enhanced Ace of Spaces (Aces of Spades?) into the deck.
How about other folks - are you all struggling with the early game as much as I am? Am I just Doing It Wrong?