A fresh evidence of the next Dota 2 hero being Puppet Master was found recently by dataminers. Originally, this champion comes from Heroes of Newereth, but since then the game was shut down.
Puppet Master's entry was first described by a Perfect World website. Gamevideo.wmupd.com added a new page with a slug of Puppet Master, which was removed shortly after. This website is used to store the data on in-game cosmetics.
Dota 2 client was also full of suspicious code strings pointing towards the new hero recently. Apart from this, an insider with the nickname Leamare announced that Puppet Master is in the row of 21 unreleased heroes from HoN that are considered by Valve as a potential newcomers to Dota 2.
The exact date of the hero's debut is still unknown to the Dota 2 community. Some believe the release will be available just before the start of the International 11.