https://www.polygon.com/2018/11/2/18056654/destiny-2-pc-free-battle-net-blizzcon-2018

During the BlizzCon opening ceremony pre-show, Destiny 2: Forsaken developer Steve Cotton announced that vanilla Destiny 2 is free for all players with a Battle.net account starting today. From now until Nov. 18, players will be able to log into Battle.net and claim their free copy of Destiny 2 in the gift section of the online client. Once the gift is claimed, it will remain part of player’s accounts forever — even after Nov. 18.

This Destiny 2 license will not include the recent Forsaken expansion, but players no longer need to purchase Curse of Osiris or Warmind in order to be caught up — both were recently added to Forsaken.