Final Fantasy XIV (FFXIV) Patch 6.11 comes with the new ultimate: Dragonsong’s Reprise. This is a Level 90 8-player raid. To unlock it you will need to have first cleared Asphodelos: The Fourth Circle (Savage). Once you have done that, speak with the Wandering Minstrel found in Old Sharlayan (x12.7, y 14.2). This is the same NPC where you unlock other Final Fantasy XIV Endwalker Extremes.
In order to enter this new Ultimate raid, you will need to use the Raid Finder. All 8 players will need to have unlocked the raid.
After clearing Dragonsong’s Reprise (Ultimate) will get a weekly reward token (Dragonsong Token). You can go to Nesvaaz in Radz-at-Han (x10.6, y10.0) to redeem the tokens for the Ultimate weapons of the Heavens.
Clearing the raid for the first time will also reward you with a title.