Radiant Citadel was awesome, one of the most original products WotC put out in years. My favorite adventure anthology. Can't wait to see if they do more with it!
They mentioned that card on their Discord:
"Lastly, a little holiday gift from us: a D&D-themed holiday card featuring art by Natalie Andrewson, showing an adventuring party making a rest stop at a warm castle on their long journey with presents and goodies in tow. Here’s to warm rolls, cold...
It's cute. The species are actually kind of interesting (I could see myself playing the fox or the snowman), and there's some cool monsters (a snow sphinx and a pine tree drake).
Yeah, pretty easy guesses, mostly. The PHB mentions the World Tree in the same vein as other methods of traveling worlds, so I thought it was the next logical one after Infinite Staircase. It could be adventures based around trees. Which would be neat. And by "Everything dropped" I think they...
My answer is amended to:
Ravenloft Players Guide
Dark Sun Players Guide
Dark Sun DM Book
World Tree Adventure Anthology
A splat book, with "Everything" dropped
According to the supplement, it only affects creatures native to Lorwyn-Shadowmoor. For those creatures, when they cross over, they "instantly take on" their other aspect, retaining only "dim, distorted memories of its time" in the other place. Nothing about PCs specifically, but as a DM I would...
Lorwyn elf - Thorn whip (replacing with any Druid cantrip on a LR), Command, and Silence.
Shadowmoor elf - 120 foot darkvision, Starry Wisp, Heroism, and Gentle Repose