Continuing with the usual tradition, MTG Arena will getting the Alchemy: Thunder Junction mini-expansion this May 7th with 30 new cards to toy around with in Alchemy, Historic, Timeless and Brawl formats. However, this release will be a bit different than usual as the new cards won't just be focused around beefing up the themes and concepts found in Thunder Junction, but also the ones found in previous sets.
Whether this is a one-and-done sort of thing or if we can look forward to more cross-pollination from future Alchemy sets, nobody outside of Wizards of the Coast currently knows, but I do like the idea. There's plenty of interesting mechanics released each year that just don't get the support they need to truly shine, so adding a couple of new cards here and there can do a great deal of good.
As far as new mechanics are concerned, there is only one to cover, though thankfully it's a very fun one. Heist is a new keyword ability that lets you target an opponent and look at three random nonland cards in their library and then exile one of them face down. You can then cast that card for as long as it remains exiled, as well as spend mana of any type in order to cast it.
What Heist looks like in action, as well as what else the Alchemy: Thunder Junction set brings with it, that you can check out at the freshly updated card gallery on Scryfall. If you just want a quick glance at Heist, however, here's my favorite card from the set:
Once Alchemy: Thunder Junction launches on May 7th I'll make sure to let you know. Until then, have fun brewing up new deck ideas!