In the Forbidden Land, Eureka, you may encounter especially powerful enemies called notorious monsters. You would do well to engage these enemies together with other adventurers if you wish to defeat them. Some notorious monsters will not appear unless certain conditions are met. Speak with other adventurers and share information that you might determine what these conditions are.
Notorious Monsters (NMs) are FATE-like boss encounters that are the primary source of loot in Eureka, including lockboxes, Allagan Tomestone of Poetics, crystals and materials needed for Eurekan Weapon upgrades, and very rare items that can be used to increase player power within Eureka and can be sold for a premium on the Market Board. NMs also provide a large amount of elemental EXP for leveling. To spawn a NM, players must defeat a sufficient number of a single, specific enemy that is 5 levels above the NM of interest. The number of enemies needed is unknown and variable: a more accurate interpretation is that defeating a requisite enemy has a low chance of spawning the NM. If the NM is still on cooldown or does not have the correct weather, defeating enough spawning mobs will "queue" the NM to spawn in the next window. The requisite enemy listed alongside the NM in the tables on the zone pages. Some NMs also have weather requirements, and requisite spawning enemies may have weather or nighttime requirements.
After being spawned, each NM has a 2 real-life hour cooldown window before it can be spawned again. This cooldown is instance-specific. Because NM respawn timers are not displayed in the game, it is not possible to tell whether a given NM is off cooldown in a given instance without asking other players, or if one is confident that the instance is newly created ("fresh"). Therefore, players use a tracker website (see Resources) for the instance to determine which NMs can be spawned ("prepped") and which ones are on cooldown. This is considered an essential tool for Eureka content and will often be discussed in /shout chat.
Similarly to FATEs in the overworld, most Eureka NMs have an elemental level sync that all players need to activate in order to participate if they are more than three levels above the NM level. Players that are two levels or lower compared to the NM level will not receive any rewards except a reduced amount of elemental EXP that the NM usually drops.
NM health scales to the number of players in the instance.
Players will usually specify a pull time (PT) to ensure that people in the instance can participate in the NM and receive rewards. This may either be in Eorzea Time or when there is a certain number of minutes remaining in the FATE timer, e.g., "PT 27" is commonly used, meaning begin fighting the boss when there is 27:00 left.
For particularly desirable NMs ("money NMs") with a low chance of dropping items that can be sold for a premium on the Market Board, players in some data centers are more likely to pull the boss immediately upon spawning it. To maximize's one's chances of earning rewards, be near the FATE spawn area a few minutes before its cooldown resets and if the correct weather will occur. It is recommended to use a tracker if available for the instance, although some Eureka-oriented Discord servers have notifications for these and other high-value FATEs (these only notify an upcoming weather window; the cooldown is instance-specific).
In order to qualify for maximal rewards, players need to achieve a gold ranking on the NM. This is easy to do if in a party (usually attacking the boss once is sufficient), so most players will form parties to fight NMs.