Let's talk about Hunts - a detailed rundown of their assumed mechanics

[Vandesaan]

Stormblood is upon us, and we've been busy.

We have far too little data to start talking about spawn timers just yet, but everything A-rank wise seems to have gone the way of 4-6 hour respawns again, just like in Heavensward. S ranks are a mystery for when you can begin spawning, but assume their timers to be the same a or equal to what we've got for Heavensward.

Useful links
Hunt spawn location maps maintained by Cable Monkey
Hunt tracking on Ariyala's
Timers for server-controlled spawns at Garland Bell

The findings
All hunt marks that are not B ranks have some basic rules to them. First, the basics. When a hunt mark dies, a timer begins ticking. All marks have a timer unique to themselves and they all tick with the server clock. The time since the hunt mark died will be your respawn time. They all have a minimum respawn time and a random variation of time in addition to that minimum spawn time. All of them have in addition to this a maximum respawn time, and S ranks have in addition to the maximum respawn time a condition that needs to be met once the respawn duration is up. A rank hunt marks have a fairly short respawn duration, going from 3 hours to 4 hours, with maximum respawns ranging from 4 to 6 hours. A rank hunt marks are special in how they will instantly spawn should they not have spawned within their maximum respawn timeframe yet. S rank hunt marks will not spawn until their spawn condition is triggered, even when their maximum respawn time has passed long ago. Note that not all S rank spawn triggers are performed by players, some are controlled by the server and you may stumble upon one in the wild.

Previously we thought there was "amount of times a condition was met" or a "threshold that had to be met". Offhand comments made to Japanese community members by development team members in past Japanese events indicate that there is no such thing, and that there simply are timeframes and conditions that need to be met. We have since gathered the maximum and minimum timeframes that have been observed and compiled this information.

The A ranks
Let's reiterate on the findings. A rank hunt marks have a fixed minimum spawn time, a random variation of time in addition to that minimum spawn time and a maximum respawn time. At the maximum respawn time, they will instantly show up in the world. They can of course show up before that, but this is a randomly assigned timeframe, so once the minimum respawn time has passed there's a timeframe in which the A rank hunt mark can spawn again, which is 60 minutes for A Realm Reborn A rank hunt marks and 120 minutes for Heavensward and Stormblood A rank hunt marks. In A Realm Reborn, the individual A ranks hunt marks are believed to have varied spawn timers due to their respawn frequency, while in Heavensward and Stormblood they all seem to have a shared respawn minimum and maximum.

Stormblood - Respawn time of 4-6 hours
Orcus & Erle - The Fringes
Vochstein & Aqrabuamelu - The Peaks
Funa Yurei & Oni Yumemi - The Ruby Sea
Gajasura & Angada - Yanxia
Girimekhala & Sum - The Azim Steppe
Mahisha & Luminare - The Lochs

Heavensward - Respawn time of 4-6 hours
Enkelados & Sisiutl - The Sea of Clouds
Lyuba & Mirka - Coerthas Western Highlands
Pylraster & Lord of the Wyverns - The Dravanian Forelands
Agathos & Bune - The Churning Mists
Slipkinx Steeljoints & Stolas - The Dravanian Hinterlands
Stench Blossom & Campacti - Azys Lla

A Realm Reborn - Respawn time varies for each mark

Zone				Hunt mark		Respawn time			Maximum respawn time
Middle La Noscea		Vogaal Ja		3 hours, 30 minutes		4 hours, 30 minutes
Lower La Noscea			Unktehi			3 hours, 30 minutes		4 hours, 30 minutes
Eastern La Noscea		Hellsclaw		3 hours, 30 minutes		4 hours, 30 minutes
Western La Noscea		Nahn			3 hours, 30 minutes		4 hours, 30 minutes
Upper La Noscea			Marberry		4 hours				5 hours
Outer La Noscea			Cornu			3 hours, 30 minutes		4 hours, 30 minutes
Central Shroud			Forneus			3 hours, 30 minutes		4 hours, 30 minutes
East Shroud			Melt			3 hours				4 hours
South Shroud			Ghede Ti Malice		3 hours, 30 minutes		4 hours, 30 minutes
North Shroud			Girtab			3 hours, 30 minutes		4 hours, 30 minutes
Western Thanalan		Alectryon		3 hours, 30 minutes		4 hours, 30 minutes
Central Thanalan		Sabotender Bailarina	4 hours				5 hours
Eastern Thanalan		Maahes			3 hours				4 hours
Southern Thanalan		Zanig'oh		3 hours, 30 minutes		4 hours, 30 minutes
Northern Thanalan		Dalvag's Final Flame	4 hours				5 hours
Coerthas Central Highlands	Marraco			3 hours				4 hours
Mor Dhona			Kurrea			3 hours, 30 minutes		4 hours, 30 minutes

The S ranks
The S rank hunt marks are a different kind of beast. They have a long minimum respawn, often for multiple days. They are similar to A ranks in how they have a minimum and maximum respawn time with a random time variation, but require in addition to that there to be a condition met for each of them before they will spawn. Some of them are completely out of players' hands and based around which day of the month, time of the day, or even how the weather has been recently. In addition, their respawn timers are different after server maintenance, with their respawn timer beginning the moment your server started up again. But that's OK; we've figured them all out, so let's have a look.

Stormblood

Zone: The Fringes
Hunt target: Udumbara (this guy is gone until Omega Savage releases most likely.)

Zone: The Peaks
Hunt target: Bone Crawler (this guy is gone until Omega Savage releases most likely.)

Zone: The Ruby Sea
Hunt target: Okina
Spawn condition: Spawns the moment the moon is full once the spawn timer is up. Because of spawn timers being random, will sometimes spend forever before it spawns.
Respawn cooldown: Insufficient data
Maximum respawn time: Insufficient data
Respawn cooldown after maintenance: Insufficient data
Maximum respawn time after maintenance: Insufficient data

Zone: Yanxia
Hunt target: Gamma
Spawn condition: With the minion Toy Alexander summoned, run or fly close to or on spawn locations throughout Yanxia when it's dark out in the game, which is from 4pm to 4am Eorzean Time. The sky begins to darken at 4pm, and sunset begins at 6pm Eorzean Time. The game begins to light up again at 4am and sunrise is at 6am.
Respawn cooldown: Insufficient data
Maximum respawn time: Insufficient data
Respawn cooldown after maintenance: Insufficient data
Maximum respawn time after maintenance: Insufficient data

Zone: The Azim Steppe
Hunt target: Orghana
Spawn condition: Spawned by successfully clearing the FATE "Not just a Tribute at around X:12 Y:14. Still unknown whether this has to be chain cleared or not.
Respawn cooldown: Insufficient data
Maximum respawn time: Insufficient data
Respawn cooldown after maintenance: Insufficient data
Maximum respawn time after maintenance: Insufficient data

Zone: The Lochs
Hunt target: Salt and Light
Spawn condition: Toss items from your inventory. If you have a stack of items, split it and toss items one by one. Recommended to not toss away a fortune while doing this, keep your littering to a minimum and come back once someone has cleaned up after you or something.
Respawn cooldown: Insufficient data
Maximum respawn time: Insufficient data
Respawn cooldown after maintenance: Insufficient data
Maximum respawn time after maintenance: Insufficient data

Heavensward

Zone: Coerthas Western Highlands
Hunt target: Kaiser Behemoth
Spawn condition: With the minion Behemoth Heir summoned, run or fly close to or on spawn locations throughout Coerthas Western Highlands.
Respawn cooldown: 80 hours
Maximum respawn time: 132 hours
Respawn cooldown after maintenance: 50 hours
Maximum respawn time after maintenance: 80 hours

Zone: The Sea of Clouds
Hunt target: Bird of Paradise
Spawn condition: Spawned by allowing the B rank hunt mark Squonk cast Chirp. Squonk only spawns in the southern part of the map, refer to the maps in the top of this post for where to look for it.
Respawn cooldown: 80 hours
Maximum respawn time: 132 hours
Respawn cooldown after maintenance: 50 hours
Maximum respawn time after maintenance: 80 hours

Zone: The Dravanian Forelands
Hunt target: Senmurv
Spawn condition: Spawned by successfuly clearing the FATE "Cerf's Up" 5 times in a row.
Respawn cooldown: 80 hours
Maximum respawn time: 132 hours
Respawn cooldown after maintenance: 50 hours
Maximum respawn time after maintenance: 80 hours

Zone: The Churning Mists
Hunt target: Gandarewa
Spawn condition: Spawned by gathering Seventh Heaven or Aurum Regis Ore. Prior to Stormblood, these nodes were once every 12 Eorzean Hours each, but with Stormblood out, these are available from 2-4 am and pm (mining) and 4-6 am and pm (botany).
Respawn cooldown: 80 hours
Maximum respawn time: 132 hours
Respawn cooldown after maintenance: 50 hours
Maximum respawn time after maintenance: 80 hours

Zone: The Dravanian Hinterlands
Hunt target: The Pale Rider
Spawn condition: Spawns when the treasure coffer of a Timeworn Wyvernskin Map is opened in The Dravanian Hinterlands.
Respawn cooldown: 80 hours
Maximum respawn time: 132 hours
Respawn cooldown after maintenance: 50 hours
Maximum respawn time after maintenance: 80 hours

Zone: Azys Lla
Hunt target: Leucrotta
Spawn condition: Spawned by killing 50 Lesser Hydra, 50 Meracydian Vouivre and 50 Allagan Chimera.
Respawn cooldown: 80 hours
Maximum respawn time: 132 hours
Respawn cooldown after maintenance: 50 hours
Maximum respawn time after maintenance: 80 hours

A Realm Reborn

Zone: Middle La Noscea
Hunt target: Croque-Mitaine
Spawn condition: Mining Grade 3 La Noscean Topsoil from an unspoiled node near Zephyr gate at 7 PM till 10 PM Eorzea time. A Grade 3 La Noscean Topsoil has to hit your inventory, missed gathering attempts do not count.
Respawn cooldown: 62 hours
Maximum respawn time: 75 hours
Respawn cooldown after maintenance: 39 hours
Maximum respawn time after maintenance: 45 hours

Zone: Lower La Noscea
Hunt target: Croakadile
Spawn condition: Linked to the current state of the moon. There are four days on the Eorzea calendar where the moon is in a full moon state, and Croakadile will spawn on the first day of full moon after 5 PM Eorzean time. Because of the 50 hour cooldown, Croakadile will skip every other month as long as he spawned in the previous month.
Respawn cooldown: 50 hours
Maximum respawn time: 50 hours
Respawn cooldown after maintenance: 30 hours
Maximum respawn time after maintenance: 30 hours

Zone: Eastern La Noscea
Hunt target: The Garlok
Spawn condition: Linked to the weather. After the minimum respawn time is up, and once the zone's weather condition is Showers/Rain, the next 200 minutes have to NOT be Rain or Showers for The Garlok to spawn. The 200 minute timeframe resets if it Rains or Showers again within those 200 minutes. The previously mentioned random time variation counts for The Garlok, so even if the 200 minute timeframe matches, your server can be unlucky with its randomly assigned time variation and not get a spawn.
Respawn cooldown: 42 hours
Maximum respawn time: 48 hours
Respawn cooldown after maintenance: 21 hours
Maximum respawn time after maintenance: 29 hours

Zone: Western La Noscea
Hunt target: Bonnacon
Spawn condition: Harvesting La Noscean Leeks from an unspoiled node near Swiftperch at 8 AM till 11 AM Eorzea time. A La Noscean Leek has to hit your inventory, missed gathering attempts do not count.
Respawn cooldown: 62 hours
Maximum respawn time: 75 hours
Respawn cooldown after maintenance: 39 hours
Maximum respawn time after maintenance: 45 hours

Zone: Upper La Noscea
Hunt target: Nandi
Spawn condition: Run close to or on spawn locations throughout Upper La Noscea with a minion summoned. See this example. Note that it is possible to summon a minion and then get on a mount and run around mounted.
Respawn cooldown: 47 hours
Maximum respawn time: 53 hours
Respawn cooldown after maintenance: 28 hours
Maximum respawn time after maintenance: 32 hours

Zone: Outer La Noscea
Hunt target: Chernobog
Spawn condition: Linked to players dying in the game world. Once the respawn time is up, someone dying will cause Chernobog to show up.
Respawn cooldown: 65 hours
Maximum respawn time: 71 hours
Respawn cooldown after maintenance: 39 hours
Maximum respawn time after maintenance: 43 hours

Zone: Central Shroud
Hunt target: Laideronnette
Spawn condition: Linked to weather conditions. Will spawn once two weather cycles (8+8 Eorzea hours) stay marked as being Rain in Central Shroud once the respawn time met.
Respawn cooldown: 43 hours
Maximum respawn time: 48 hours
Respawn cooldown after maintenance: 25 hours
Maximum respawn time after maintenance: 29 hours

Zone: East Shroud
Hunt target: Wulgaru
Spawn condition: Initiate a Battlecraft Levequest. This means accepting it and hitting the Initiate button in your Journal to start challenging the Levequest.
Respawn cooldown: 66 hours
Maximum respawn time: 78 hours
Respawn cooldown after maintenance: 40 hours
Maximum respawn time after maintenance: 47 hours

Zone: South Shroud
Hunt target: Mindflayer
Spawn condition: Linked to the current state of the moon. There are four days on the Eorzea calendar where the moon is in a new moon state. Mindflayer will spawn after midnight on the second day of new moon.
Respawn cooldown: 50 hours
Maximum respawn time: 50 hours
Respawn cooldown after maintenance: 30 hours
Maximum respawn time after maintenance: 30 hours

Zone: North Shroud
Hunt target: Thousand-Cast Theda
Spawn condition: Catch a Judgeray. Requires at least 330 Gathering, can be caught in the period of 5PM to 9 PM Eorzea time.
Respawn cooldown: 58 hours
Maximum respawn time: 68 hours
Respawn cooldown after maintenance: 35 hours
Maximum respawn time after maintenance: 41 hours

Zone: Western Thanalan
Hunt target: Zona Seeker
Spawn condition: Catch a Glimmerscale. Requires at least 300 Gathering, can be caught at any time of the day as long as the weather condition is Clear Skies or Sunshine.
Respawn cooldown: 58 hours
Maximum respawn time: 68 hours
Respawn cooldown after maintenance: 35 hours
Maximum respawn time after maintenance: 41 hours

Zone: Central Thanalan
Hunt target: Brontes
Spawn condition: Eat a piece of consumable food near a spawn location in the zone. Any place you have seen any of the S, A or B rank hunt marks spawn count.
Respawn cooldown: 64 hours
Maximum respawn time: 78 hours
Respawn cooldown after maintenance: 40 hours
Maximum respawn time after maintenance: 46 hours

Zone: Eastern Thanalan
Hunt target: Lampalagua
Spawn condition: Initiate a Battlecraft Levequest. This means accepting it and hitting the Initiate button in your Journal to start challenging the Levequest.
Respawn cooldown: 66 hours
Maximum respawn time: 78 hours
Respawn cooldown after maintenance: 40 hours
Maximum respawn time after maintenance: 46 hours

Zone: Southern Thanalan
Hunt target: Nunyunuwi
Spawn condition: Linked to the repeated completion of FATEs over a period of time. Do not let a single FATE fail or expire for 60 minutes.
Respawn cooldown: 44 hours
Maximum respawn time: 54 hours
Respawn cooldown after maintenance: 26 hours
Maximum respawn time after maintenance: 34 hours

Zone: Northern Thanalan
Hunt target: Minhocao
Spawn condition: Linked to the acquisition of Earth Crystals by people in the zone. Drops from Earth Sprites, both existing naturally in the world and from the ones that massively spawn during the FATE 'Core Blimey'.
Respawn cooldown: 57 hours
Maximum respawn time: 63 hours
Respawn cooldown after maintenance: 34 hours
Maximum respawn time after maintenance: 41 hours

Zone: Coerthas Central Highlands
Hunt target: Safat
Spawn condition: Hit critical HP (below 5% health remaining), either by fighting monsters till they almost kill you, or simply by jumping from heights to hit 1 HP.
Respawn cooldown: 60 hours
Maximum respawn time: 84 hours
Respawn cooldown after maintenance: 36 hours
Maximum respawn time after maintenance: 50 hours

Zone: Mor Dhona
Hunt target: Agrippa the Mighty
Spawn condition: Open the treasure coffer of a Peisteskin treasure map somewhere in Mor Dhona. Does not count for Deciphering maps, you have to open the treasure coffer after beating the monsters summoned by the map.
Respawn cooldown: 60 hours
Maximum respawn time: 84 hours
Respawn cooldown after maintenance: 36 hours
Maximum respawn time after maintenance: 50 hours