When the feature launched, it came with a stark warning regarding trading virtual cards for real money, in which the developers said, "If we confirm that a player has engaged in behavior that violates the Terms of Use, we will warn them, suspend their account, or take action." The guidelines laid out are pretty clear: don't profit from the app
You have to buy cards the same way you would IRL, but theyre much cheaper
(2021-07-23) You can multiclass or even control multiple Class enchantments of the same class
If youre playing [c]Cancel[/c], which costs three mana, Id replace it with [c]Counterspell[/c], which costs two
Sources: PWCC/U Magikarp, PWCC/GS Umbreon, Heritage Auctions/No
As if Delighted Halfling hasnt done enough to claim their spot on this list already, theyre also a better body than Llanowar Elves