Magic: The Gathering promo cards come in all shapes and sizes. Some are simple one-and-dones given out for a special event. Others were made especially for Richard Garfield for certain events in his life. And yet others still are borne out of strange cross promotions.
Every holiday season, however, Wizards of the Coast manages to pull out a holiday-themed Magic cards for their parties. Ever since 2006, an odd Christmas- or holiday- themed card has come out as a gift for both employees and for those with business ties to WotC. Some years it wasn't even that simple, and they were simply given out as 'mystery gifts'.
Back in 2006, it was originally just planned as a single holiday event never to be repeated, as they said at the time that it was simply a rare promotional card. But they became so unique and popular that Wizards of the Coast made another in 2007. And another in 2008. And, even to this day, we can count on a new holiday card to come out.
The cards have gotten inspiration from everywhere. Many of them have been Christmas-ized variants of popular past cards. For example, in 2007, Gifts Ungiven was parodied to Gifts Given. And in 2014, Mishra's Workshop proved the inspiration for Mishra's Toy Workshop. Even this year saw a re-imagining, with Dream Halls becoming Topdeck the Halls.
During other years, moves and creatures inspired by Christmas sayings or symbols took prominence. 2012 had the sorcery cards Naughty and Nice. 2013 went even crazier, putting up a killer stocking out as a creature, aptly named Stocking Tiger (also a play on words from the Portal Three Kingdoms card Stalking Tiger).
Other ones even use public domain source material, as seen with 2018's Bog Humbugs being unveiled, taking a bit away from Charles Dickens' A Christmas Carol.
While back in the day these cards were a little easier to get your hands on (the first, Fruitcake Elemental, went to a lot of people attending a Magic event in 2006), recent ones have become so hard to get and wanted that many who have had them now regret selling or giving them away. Who doesn't like Christmas after all?
While some sets tend to focus on something more (more-or-less) seasonally themed, like the gothic horror themed Innistrad and the future Innistrad Werewolves and Vampires being more of a Halloween-type set, Magic never really makes something directly based on a holiday. But their holiday cards are all a little bit different in that it's their focus.
And, if you go by market price, they're still as popular as ever.