The first Artifact public demo will be held at PAX West 2018 in early September, and participants at that event will be able to get beta keys to spread around. Artifact will launch on November 28 for US$19.9 9 on Steam and will feature two 54-card pre-constructed decks plus 10 sealed card packs with 1 guaranteed rare card.
https://www.notebookcheck.net/Valve-to-launch-its-Artifact-card-game-on-Novoember-28.320286.0.html