From Patch 14.19 Notes

“The mid-set for our fifth set, Dawn of Heroes, changed a lot for TFT. It brought Radiant Items into the game, introduced the Divine Blessing (which later inspired a few Portals), added the Tome of Traits (recently closed), and added a bunch of new Champions like Akshan! If you’re excited to relive memories from 3 years ago (yikes, what is time?) or boldly explore a new-to-you set with Sentinels, the Forgotten, and my favorite Hellion, then hop right in with a newly updated Dawn of Heroes Revival from September 25th, 4:30 PM PT – Nov 4th, 4:30 PM PT!

The Dawn of Heroes Revival launches with a new Ranked Revival Ladder that tracks your progression with your playstyle and skill in mind. Climb through the Ladder to earn rewards! To learn more about the Revival and the new Ranked Ladder, check out our first-ever Dev Double Up here!”