Their symbol is two pastel stars, one pink and one green, a color combination no other rarity uses
Weve got a full list of them , but for now, weve narrowed down our top 12
To be precise, only 12 Hideaway cards currently exist in MTG according to Gatherer
If you just paid some life and named two colors when you played a fetchland, and that land tapped for mana of those two colors for the rest of the game, theyd be better than all the other lands in Modern, but on top of that, they trigger landfall twice, count toward delirium, trigger revolt, allow you to shuffle your deck if you need to, and interact with a variety of other mechanics, as well as marginally thinning your deck. Fetchlands are fantastic, and were allowed to play up to 40 of them, but even though people play twenty to 24 lands, they rarely play more than twelve fetchlands
See the example below