Two new Rygelon achievements were hotfixed on live servers. They require you to defeat Rygelon while under the effects of Herald of the Cosmos on Heroic / Mythic difficulty before the release of the first raid tier in Dragonflight.
You can currently earn both achievements on live servers, but they don’t reward anything.
We Are All Made of Stars (Heroic) – Defeat Rygelon with all players under the effects of Herald of the Cosmos in the Sepulcher of the First Ones on Heroic Difficulty or higher, before the release of the next raid tier.
We Are All Made of Stars (Mythic) – Defeat Rygelon with all players under the effects of Herald of the Cosmos in the Sepulcher of the First Ones on Mythic Difficulty, before the release of the next raid tier.