Planeswalkers have always been featured on some of the most powerful cards in Magic: The Gathering and soon it will be possible for everyone to easily acquire one, as the upcoming War of the Spark set will have a planeswalker in each booster pack.
War of the Spark is based on narrative events happening in Magic: The Gathering involving a war between different Planeswalkers and an elder dragon who is trying to achieve godhood. The events mentioned in the War of the Spark cards will be detailed in an upcoming novel called Ravnica: War of the Spark, which is due to be released on April 23, 2019.
The abundance of Planeswalkers involved in the conflict means that the War of the Spark set will feature thirty-six new planeswalker cards, which have been depicted as part of stained-glass windows in the official teaser trailer for the set.
The artwork for the stained-glass Planeswalkers was shown in more detail in a recent post on the official Magic: The Gathering website, where it was also revealed that each War of the Spark booster pack would have one of the thirty-six planeswalker cards in them.
It has since been revealed on the Tumblr page of Mark Rosewater (the head designer of Magic: The Gathering) that the thirty-six planeswalker cards are all going to be brand new cards, even if they depict returning characters, which means that none of them will be reprints from older sets.
The majority of the thirty-six Planeswalkers are characters who appeared in previous Magic: The Gathering sets, such as Jace Beleren, Liliana Vess, and Vraska, but there are a handful of unknown Planeswalkers whose allegiances and capabilities are currently unknown.
War of the Spark will also have at least two planeswalker decks, though it's not yet known which Planeswalkers will be featured or what kind of cards the decks will include.
The cards from the War of the Spark expansion will be released on May 3, 2019. The prerelease for War of the Spark begins on April 27, 2019. The War of the Spark cards will also be coming to MTG Arena on April 25, 2019.