Amirada spawns on every Friday at 16:00 EST.
Amirada can be accessed through a cave entrance North-East of the depot in Cyntara City.
Defeating Amirada will reward the world with +100% experience rate and the surviving players with loot.

The World Ender spawns on every Saturday at 16:00 EST.
The World Ender can be accessed through a portal in the Draconia spawn.
Defeating the World Ender will reward players with exclusive endgame items.

Loraxtuz can be found on the Frazellar Island after finishing a world task for Sturius. Talk to Sturius to find more about the task.
Defeating Loraxtuz will reward the world with +100% loot rate for 24 hours.

Harbinger of Death can be found on the Eidola island after finishing a collaborative world task for Sevim. Talk to Sevim to find more about the task.
Defeating the Harbinger of Death will reward the world with +50% experience rate bonus for 24 hours.