Magic: the Gathering Arena is the new hotness from Wizards. It’s had the best interface for a while, and WotC recently added the Cube and the ability to draft against other humans. This is the way to play limited online in 2020.
For constructed, Cockatrice is decent, free (as in proxies), and supports multiplayer. It’s a little trickier to get running though:
- Install cockatrice and run the Oracle tool.
- Build or import a deck. This part is pretty slick: you can build a deck by hand or export a text file like Omnath, Prossh, or the Ur-Dragon from TappedOut or DeckBox. Import the text file and Save-As *.cod.
- Menu: Cockatrice -> Register to server…
- Create an account, and consider supporting Rooster Ranges.
- Menu: Cockatrice -> Connect
- Create or join a game.
The Cockatrice Discord is a good place to find people to play with.