Quite a few years have gone by since Pioneer Masters was first announced, but it looks like the long wait will soon be over. According to a recent announcement, MTG Arena will be getting the entirety of competitive Pioneer on December 10th, 2024 thanks to the Pioneer Masters set.
What this means is that MTG Arena will not have every single card that's currently legal in Pioneer, but rather any card that has seen even fringe competitive play. And if any random card ever becomes popular and successful enough to reach top 8 in a major tournament, Wizards of the Coast have said they'll make sure to add that as well.
The exact list of Pioneer Masters' 394 cards has not been revealed just yet, but Wizards of the Coast did release some small teasers. Most notably, you can look forward to Hidden Strings which is an important part of the Lotus combo deck, as well as Jace, Vryn's Prodigy which is just a generally good blue card.
The final thing worth mentioning is that Pioneer Masters will be a fully fledged set with its own limited formats. As a draft enthusiast this does sound quite exciting as a set made entirely out of competitive staples should, at least in theory, produce a rather unique and interesting experience.
Whatever the case may be, I'll make sure to let you know once Wizards of the Coast finally spills the beans and announces all of the cards. Until then, you might also want to check out the latest Universes Beyond announcement as it looks like every cross-over set will be legal in every format from this point onward!