The Fire-Feathered Serpent World Change/Spoiler

This world change is related to the Twenty Miles Beneath the Sea Quest. One distinctive characteristic of it is that its change of states occur immediately after being triggered, and not after the next Server Save as with most World Changes.

Method
The Seacrest Grounds can have two states, which are a reflection of the situation of the Fire-Feathered Serpent. Usually, the serpent is asleep and you will find regular Quaras, Sea Serpents and Seacrest Serpents in the Seacrest Grounds. During this stage, Guide NPCs will inform the following state:

Once a number (1500?) of Seacrest Serpents are killed across the Game Worlds, the World Change will not be triggered, yet, but there will be a server-broadcast that the Serpent is being awakened:

The Guide NPCs will also give a different answer:

As soon as 3000 Seacrest Serpents are killed, the World Change will be activated, and the regular Quaras, the Sea Serpents and the Seacrest Serpents will be replaced by Renegade Quaras. The following message will be broadcast to all players:

When this happens, the The Fire-Feathered Sea Serpent mission of the quest will become available. If you want to complete this mission or fight the Renegade Quara, you should hurry to the Seacrest Grounds as it usually don't last very long.

Once 1000 Renegade Quaras are killed, the Fire-Feathered Serpent will go back to sleep, and the world change will return to its default stage.