Valve has removed Lone Druid from the list of selectable heroes in Dota 2. The hero is still available for testing in the practice mode but cannot be picked in matchmaking or even in private lobbies.
The developers have not commented on this decision. It is believed that the removal is due to a bug that allows players to crash servers while using Lone Druid. Complaints about this vulnerability have previously appeared on Reddit and the Dota 2 issue tracker on GitHub. As of the time of publication, the issue has not yet been resolved.
In July, Valve temporarily removed Meepo from Dota 2 due to numerous bugs associated with the hero. The developers excluded the hero from the pool on July 3, and he was made available again the following day.