Eris not unlocking

[Landon Keyser]

Had two games using the checkered deck, played all five jokers of heart and it hasn't unlocked. Do I need to unlock Five of a kind before flash five unlocks?

[malogoss]

There's no prerequisite to playing 1 of the 3 secret hands. Then the planet starts appearing, also without prerequisite. There's no "order" in which to unlock secret hands and planets, to directly answer your question.

You can play any of the 3 secret hands at any time. It will be scored as such, priority to the strongest hand contained in the cards you played.

To be able to find a planet card associated with a secret hand, you first need to play that secret hand at least once during a run.

Once you've played that hand, you can find the associated planet card in the shop or in packs. If you use one such planet card, it will be unlocked in your collection (it might be enough to simply have one in inventory, but idk, I'd take no risk and use it right away).

But it being unlocked in your collection does not mean you'll find that planet card randomly in your future runs. You won't. You always need to play the hand once to then have a chance to find the planet card in any run.

Bonus info:
Blue seal cards will work as expected in all cases. Using the planet card generated by a blue seal (or simply generating one, but as mentioned above, idk, so don't risk it) will unlock that planet card in your collection, if it is not unlocked yet.

However, as you may already know, seeded and challenge runs prevent you from unlocking any card in your collection, including planet cards. You could find and use Eris in a challenge run, for example. But it would not unlock it in your collection.