We got the win tonight.
Party comp: WHM/NIN (ML46), RDM/NIN (ML40), BRD/NIN (ML29), COR/NIN (ML42), NIN/WAR (ML45), RUN/BLU (ML31)
Kill order: AATT > Orbitals x2 > Eald'narche > Kam'lanaut > AAGK > AAHM > AAMR > AAEV.
General encounter notes: outside buffs carry in. Traditional super tanking is possible, and is what we used. There is no WS wall/decay mechanic. Unsure if there is any Prime weapon damage bonus in there, as none of us used a Prime weapon for it. Naegling Savage Blade spam from everyone (mostly); AAGK and Behemoth are the two definite exceptions to this as they take very poor physical damage (Leaden does very well on them, as does SC damage). Both BST pets and AAGK's wyvern are not win conditions and do not need to be killed for the encounter to end. Killing orbitals levels up Eald'narche (one level up from each), and killing AA's levels up Kam'lanaut. Defense Down from NIN's Ageha landed for a full 3mins on everything in the encounter. Aisha: Ichi also landed easily with water threnody on the mobs that we specifically wanted to get it up on (Kam'lanaut, AAGK, and AAHM).
Tanking approach: RUN super tanks in the entrance doorway, and the NIN peels off targets one-by-one and shadow tanks them, with the exception of AAEV and AAMR, who were both deliberately saved for last and tanked by the RUN. Almost everything in this encounter is absorbable by shadows, making NIN an attractive "off-tank" and DD. Throughout the fight, the tank will often be dispelled from Kam'lanaut (and occasionally full dispelled from Tortoise Song from the Adamantoise). We prioritized getting at least a couple Minne's + Gallant's back up on the tank if he lost them.
Songs: Honor, x2 Madrigal, Minuet 5, Minne 5. We also had Herc Etude, a 2nd Minuet, a 2nd Minne, and Scherzo from an outside bard going into the fight, which all lasted a good portion of the way through Eald'narche. During certain stretches, we dropped the 2nd Madrigal for an extra Minuet. On Eald'narche, AAMR, and possibly AAEV, x2 Madrigals felt necessary (with the Madrigals/Honor needing to be Soul Voice'd for Eadl'narche).
Rolls: Crooked Chaos + SAM. Crooked Gallant's from an outside COR initially going into the fight. We chose to maintain Gallant's on the RUN for the first half of the encounter until fewer mobs were smacking him.
AATT / Orbitals
Physical damage on all three of these mobs. As the tank is pulling the pack to the doorway, the NIN provokes AATT off as he runs past and AATT is killed while the tank is getting into position, also allowing time for the Orbitals to be summoned. The Orbitals should be silenced - they can pump out fairly strong -ja's, Dispelga, and other AoE debuffs including para and silence.
Eald'narche
The most annoying mob of the 12 in the encounter, and the main reason most of the party comp is /NIN. He seems to have potent regain, and spams
Vortex, an AoE 15-second terror, bind, and hate reset. He summons x2 Orbitals roughly 15 seconds after aggro, and he gains significant DT from the Orbitals while they're alive, so those are killed before Eald in the kill order. The terror duration seemingly cannot be reduced - Idris Bolster Vex/Attunement + Odyllic still resulted in a full 15sec on terror. It is absorbable by shadows, and since it's a hate reset, shadow tanking is perhaps the only reliable way to tank him. Eald also casts Tier 6 nukes, which can one-shot any non-tank without shadows (Scherzo from an outside BRD, and Migawari are big value for this reason as perfect shadow upkeep isn't trivial). Eald's enmity seems very strange to us and he is the one mob in the encounter that cannot be super tanked as he will constantly teleport around to random people, but we were able to lock his enmity on a target (NIN) provided we were shadow tanking him - the hate reset from Vortex will never land if the NIN can maintain shadow upkeep, and everyone else can (mostly) mitigate the Terror spam via /NIN (Vortex seemed to absorb a random number of shadows ranging from 1-4). On pull, we waited for Eald to summon his orbitals, then we Sytmie + Sleep Eald while we kill AATT + x2 Orbitals. The investment of Stymie there is primarily to avoid the chaos of Eald porting around terror'ing random targets until we are actually ready to kill him. At 40% on Eald, AAMR will use Charm. At 25% on Eald, AAEV will use Benediction. At 10% on Eald, AAHM will use Mighty Strikes. These uses of the AA abilities that are based on Eald's HP% do not prevent these AA's from using the same abilities later when you are fighting them. The meaningful one there is charm, but since it's predictable, our RUN used Odyllic/Tenebraex3/Pflug when 40% on Eald was approaching. Eald is incredibly evasive (not sure how much of this is attributable to the level ups from the Orbitals, but given how potent the DT is from the Orbitals, I don't think you can avoid killing them both first). Soul Voice Honor March, x2 Madrigals, and Distract 3 felt like a must.
Kam'lanaut
Has access to
Great Wheel, which is a physical AoE that hurts - without shadows, this move can one-shot DD's. Since we chose to kill AATT before fighting Kam'lanaut, he had one level up when we fought him, but we had previously killed him before any AA's were killed and we did not notice a meaningful difference in his damage taken, nor damage dealt from just a single level up. Kam'lanaut can cast Dispelga, so silence needs to be upkept on him because he takes a while to kill. It typically took a few immunobreaks to land it, and doesn't last very long. As with other versions of Kam, he absorbs elemental/SC damage aligned with his en-spell element, but Savage Blade spam makes this a moot point.
AAGK / Behemoth
Both of these mobs take very poor physical damage, but good magic damage. Leaden and other magic WS's do well on both. Bio for AAGK, as he can get spammy with Dragonfall, a pretty threatening AoE WS.
AAHM
Takes full physical damage, but hits extremely hard (he can use Mighty Strikes multiple times; he used MS 15 times in our win) and burns through shadows extremely quickly with multi-attacks. Has access to Mijin, so we Sacro'd at 50%.
AAMR
Extremely evasive, and in addition to the predictable charm she uses when Eald reaches 40%, she can also seemingly use charm at any time. Since the first Charm is predictable and we were ready for it, it missed the RUN with x3 Tenebrae, a Light Carol, Pflug, and Odyllic. The 2nd Charm missed with basically just Tenebrae x3.
AAEV
Spams Shield Strike, putting the tank in stun jail. She is seemingly the tank-iest mob in the encounter in terms of damage taken from any type, though her HP is far less than the two brothers. She will Bene once when Eald is at 25%, and can bene later on when you are fighting her. Around 25%, she gains access to single target Spirits Within (not the AoE version, Arrogance Incarnate). It one-shot our RUN for 8.2K when she was at 17% HP. Another for 6.1K damage with 6% HP, and 1.5K damage with 3% HP. One way to deal with this is to gravity kite her from 25%-0.
Adamantoise
Has access to Tortoise Song, and unlike Tolba, Silence does not prevent him from using it. Can be slept, but not easily. He also has access to Tortoise Stomp, the defense down from which should be removed from the tank asap.