Good point about Ysera the Dreamer here. There’s another puzzle where it’s relevant, namely the Nathria one.
An important thing to note, although it’s been said elsewhere: Core versions of most pertinent cards (with the likes of Ysera actually being the exception), in this case the Lunar Eclipse, do not work for these puzzles [1] — you’ve gotta use the ‘evergreen’ ones, that is, the craftable ones. Especially with the Nathria puzzle, it’s a big ‘ouch’ for those who hadn’t done it when it was still free — I had to craft a bunch of expensive cards… However, Ysera the Dreamer and Nozdormu the Eternal are the exceptions there, existing only in the Core set for now, so now is probably the time to do it (and the puzzle itself is actually fun, unlike some others, and involves some actual play), lest it become even more expensive with her rotating out.
[1] https://twitter.com/Celestalon/status/1674544679067721728
PS Whoops…