DOTA Team said;
The new Ranked Season of DOTA will go live with 06.06.2018 update. As we kick off the season, your new Ranked Medal will be calculated through a calibration period of ten games. This season’s calibration will allow for a substantial change in rank based on your performance during calibration, seeded by your previous rank. Your previous season’s medal will be displayed in your profile, alongside your new medal.
We’ve made some changes to the Ranked Medal system itself. You’ll now be able to see the progress on your profile medal, visible only to you, to track your advancement towards the next star or rank. Additionally, the steps between ranks go from 1 star to 5 stars, instead of 0 to 5. There is also a new tier of Ranked Medal exclusively for players positioned on the Leaderboards — designated as Immortal — to help more clearly distinguish the top players in the world. The Immortal rank does not have stars, just the explicit leaderboard ranking.
As always, Rank Medals represent your highest performance level for the current season, and a medal will never decrease in rank once you’ve earned it. Once you’ve calibrated your new ranking, there’s nowhere to go but up.