Frostivus will return for the 4th year this December as part of the holiday season fun within the Dota client. The event generally takes place during the Christmas season and has been thrice till now - 2012, 2013 and 2017.
Workshop artists, don't forget to submit your items before the deadline --Frostivus returns mid-December.— DOTA 2 (@DOTA2) October 27, 2018
2012 saw the Greevling mode being introduced into the Dota client along with Treasures and cosmetic items. In 2013, the Wraith Night game mode was introduced which was sort of like a co-op tower defence game. It was also the year when Skeleton King was rebranded into Wraith King. After giving it a miss in the following years, Frostivus returned last year in 2017, with a series of custom games. A set of 10 games was randomly selected for each match and players were scored across them all to decide a final winner.
Unfortunately, though, none of the Frostivus modes have been extremely popular unlike the Diretide game modes which came out during in 2012 and 2013 during Halloween. The Wraith Night mode was enjoyable but the Greevling mode had way too much complexity for it to be a casual mode. The mini-games in 2017, on the other hand, were too simple and didn’t have the level of depth required to make them engaging. But all we can do is hope that Valve has something exciting planned for us this time around.