Limbus



Image source: https://enedin.be/ffxi/

Whygee's Nightbrood Limbus Guide
Refer to the info-graphic above for this guide.

Zones

 * Apollyon (Proto-Omega) - DARK elemental - Set drop: Homam
 * Temenos (Proto-Ultima) - LIGHT elemental - Set drop: Nashira

Entry requirement & Best approach

 * 1) Everyone always needs a Cosmo Cleanse from the Bard in Port Jeuno (right outside the Windurst Airship Port). Acquiring this KI is on a day-long timer from the moment of acquisition, not the moment of use (very important distinction).
 * 2) Everyone always needs a Card of a certain color from a Aw-Euvhi parked outside the area you are visiting in Al'Taieu. They respawn every 10~ish minute so it's pretty much always available.
 * 3) Only the person who triggers the event burns their Cosmo Cleanse & Card. Considering points 1 & 2 above, it means it is possible for a small dedicated group to get the boss pop item in a few hours.

Guiding Principles - Apollyon

 * 1) Apollyon West (North/South) from HP2 with Red card from flower
 * 2) Apollyon East (North/South) from HP3 with Black Card from flower
 * 3) Victory in each zone gives a chip. Once you have all 4, combine them in either West/East to be granted access to P-Omega.
 * 4) Always try to bring a balanced party to Apollyon and have a dedicated sleeper in case. Kill enemies in small groups at a time and check if the teleport (i.e. the squarish arc structure) activated after each. Sometimes it's more obvious than others (i.e. there's a big bad).
 * 5) The mimic that will trigger the teleport in SW 3F is the one dead centre in the entrance/exit axis. All the others are bugged and will lead to a GM call.
 * 6) The correct Elementals to kill in SW 7F are the ones from the day you entered (i.e. Firesday = kill the Fire elementals to trigger the win).
 * 7) Be advised that sometimes, even though you entered the East area, you will land in the West area after completing the zone, and vice-versa. It's a bug, so just get out and regroup at the right spot.

Guiding Principles - Temenos

 * 1) Temenos is always HP1 with White Card from flower.
 * 2) Temenos is on a 2-tier system of West-East-North leading respectively to 1st-2nd-3rd. Victory in tier1 provides the chip to trade to access its respective tier2, and all 3 tier2 chips will together grant access to P-Ultima.
 * 3) Party composition should be melee heavy in West/1st & North/3rd - Ninjas, Warriors, Monks and Samurais will crush everything, pair them with a BRD for the added lols (Ninja self-chains, yes please). Meanwhile, you should be mage heavy in East/2nd to deal with the elemental onslaught.
 * 4) Last time we were there, opening a chest while engaged to mobs would automatically despawn the mobs and count as victory. Pretty weird. Be careful not to lock yourself out of being able to kill the last monster that will drop the chip on the last floor.
 * 5) Proceed through the floors murdering everything until you arrive at the gate crystal and move on to the next murder spree. The last group to die on the last floor will spawn a chest with the required progression chip.

Chests

 * TreasureChest TE.png Blue = Time extension (rarely needed)
 * TreasureChest AF+1.png Shiny Brown = Item - required for AF+1 upgrades
 * TreasureChest HP-MP.png Matte Brown = HP/MP restoration (rarely needed)

* Be advised that often, it will take a little while for chests to materialize after the kill, so don't go running off without your loot! Generally speaking, you can open all chests in Apollyon (exception: SW 3F; see above) and one per floor on Temenos. But I think it's bugged and you can do more.

That covers the basics, the rest is experience in the zones and fun times with friends