[Update]: MTG Arena's Alchemy: Murders at Karlov Manor mini-set is launching on March 5th, and it brings with it a potential teaser for 4-player games!
Instead of having Draft Boosters and Set Boosters, Magic: The Gathering will soon be consolidating both into brand new Play Boosters. These Play Boosters will contain 14 cards, will be fully draftable, and will have a chance to contain some fancy cards from days gone by, including some with unique new artwork.
For MTG Arena in specific, these Play Boosters will be present in Limited formats, while the current 'normal' boosters will continue to be given out as rewards and will remain available for purchase through the in-game store. So if you don't play Limited or care about the older formats like Historic, Timeless or Explorer, chances are you might not even notice anything has changed.
You can check out the full list of these extras, including both The List cards and the Special Guests, over at the MTG website. There's quite a few good ones in there!
That's not all the big news, however, as MTG Arena is also getting the brand new Murders at Karlov Manor set this February 6th! The crime focused expansion will bring with it a modernized version of Morph, plenty of Clue Tokens, and as you'd expect, some new and some returning mechanics all focused around crime, solving crime, as well as doing your darnest to make sure said crime remains unsolved!
You can find the full list of Murders at Karlov Manor cards, all neatly sorted by color, over at the official card gallery. And if you're curious about all of the details behind the new mechanics and how they work in weird corner cases, you should also check out the release notes for the set. Though to be warned, there's quite a lot of them to go through.
Enjoy!