How to Unlock Theros Beyond Death Basic Lands
Theros Beyond Death came with 15 new Basic Lands, comprising of 5 of the special full art Nyx lands and 2 of each of the normal bordered lands that usually come with each set release. However, most players are finding that they are not available to use for them within the MTG Arena client.
It had already been announced that information on how to obtain these special Nyx lands will be available at a later date along with the other showcase cards from the set (such as these Constellation ones here), but you may have seen some players using these lands already within the game.
You can currently obtain the Plains, Island and Swamp versions of the Nyx Lands in MTG Arena by obtaining the Planeswalker Decks and redeeming the code for the deck inside. Whether this is intentional by Wizards or not (because the decks themselves do not come with these lands) is not known yet, but you can get it earlier than others as these are expected to be part of event rewards (most likely with an entry fee) or as a purchase from the in-game store. This has been confirmed an unintentional error, and has been fixed with the 1.04.01.00 patch – you will no longer be able to get the Nyx lands via the Planeswalker Decks.
As of the February 11 1.05.00.00 patch, you will be able to purchase them for 3000 Gold each from the in-game Store.
Normal Basic Lands
Theros Beyond Death still comes with the normal bordered Basic Lands and this time we have two of each (rather than the usual four) because these are actually part of the supplemental products for tabletop Magic, whereas the Nyx Lands shown above are actually part of the main set. These lands are usually made available to all players when a new set releases, but players may find that these ones are also not available to use as well.
This is actually a known issue, communicated in the latest hotfix that should be fixed in another patch some time next week.
Land Export Codes
For your reference, here are the MTG Arena export codes for the new Basic Lands of Theros Beyond Death.
Deck 1 Plains (THB) 250 1 Plains (THB) 278 1 Plains (THB) 279 1 Island (THB) 251 1 Island (THB) 280 1 Island (THB) 281 1 Swamp (THB) 252 1 Swamp (THB) 282 1 Swamp (THB) 283 1 Mountain (THB) 253 1 Mountain (THB) 284 1 Mountain (THB) 285 1 Forest (THB) 254 1 Forest (THB) 286 1 Forest (THB) 287