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Castrum Fluminis is a level 70 Trial inFinal Fantasy 14, added in Patch 4.3, Under the Moonlight. After Tsuyu is brutally forced to relive her past and regain her memories as Yotsuyu, and with Asahi’s stash of aether-infused crystals, Yotsuyu transforms into the divinity of the night, Tsukuyomi.
With Hien in pursuit of Asahi, it’s down to you to stop Tsukuyomi before she plunges Doma into an eternal night. Below, we’ll take a look at everything you need to know about this Trial, including how to deal with each of Tsukuyomi’s mechanics in each phase of the fight.
How To Unlock Castrum Fluminis
Castrum Fluminis will unlock through the Main Scenario Quest’The Primary Agreement’during thePatch 4.3 questline. This Trial has anitem level requirement of 335to participate.
Tsukuyomi Fight Walkthrough
Phase 1
In the first phase, Tsukuyomi will use the following attacks and mechanics.
Torment Unto Death
Tankbuster
Deals high damage in acone to the front of the boss, targeting Tsukuyomi’s main target. The Tank shouldface the boss away from the rest of the partywhile usingdefensive cooldownsto reduce the damage of this attack.
Zashiki-asobi
AoEs
Tsukuyomi will summon fans around the arena;one in the center, then a series ofsix in a circle surrounding the edge of the arena. Then, these fans willexplode in an AoE, starting with the center fan andcontinuing in the order they were summoned. Look to where the first AoE appears andmove to thesafe spot beside it until the center fan explodes, then step into the center to avoid the rest. As the fans resolve, Tsukuyomi will castNightfall.
Nightfall
Special
Randomly castsSteel of the Underworld,Reprimand,Midnight Haze, orLead of the Underworld. Tsukuyomi will use this attackduring Zashiki-asobi, as the fans explode.
Steel of the Underworld
Conal AoE
Deals damage in alarge cone to the front of the boss. Move out of the AoE indicator to avoid taking damage.
Midnight Haze
Summon
Tsukuyomi will summon twoMidnight Haze cloudsat opposite ends of the arena that will tether together,slowly moving toward each other. If the clouds touch, they will explode, damaging all party members.Destroy both cloudsbefore this happens.
Lead of the Underworld
Line Stack Marker
Targets a random player with a Stack Marker.Group up on their positionto spread out the damage of this AoE.
Tsukuyomi will end this phase withNightbloom, dealing damage to the entire party, that inflictsDown for the Countfor a few seconds, preventing you from taking action.
Phase 2
Once you can move again, several adds will appear and being targeting Tsukuyomi. As the adds attack, they will fillTsukuyomi’s Suffering gauge, which will indicate how much damage her phase-ending attack deals later.
Group up anddefeat each wave of adds to protect Tsukuyomi. Eventually, theSpecter of Zenoswill appear and castConcentrativity, dealing damage to the party and inflicting Stun and Down for the Count. Once you can attack,defeat Zenos’s Specter to end the phase.
Tsukuyomi will castNightbloomagain,dealing damage according to her Suffering gauge. If the gauge is at 100, this willinstantly kill everyone, so you’ll need to get through the add phase before this happens. After Nightbloom, phase three will begin.
Phase 3
During this phase, Tsukuyomi will use several attacks from phase one, as well as a few new ones, which are detailed below.
Selenomancy
Divides the arena into awhite halfand ablack half. Standing in the white half will slowly accumulate stacks ofMoonlit, while standing in the black half will accumulate stacks ofMoonshadowed. If either debuff reaches5 stacks, you will be inflicted withDoomandBleed.
Moving to the opposite half of the arena will begin removing stacks of the other side’s debuff. To avoiding being inflicted with Doom, you’ll need to occasionallyswap between both halves of the arena.
Moonlight - Lunar Halo
Ring AoEs
TwoMoonlight orbswill appear, one on either side of the arena. These will then castLunar Halo, dealing damage in alarge ring AoEwith asafe spot near the orbitself. Swap to the other side of the arena to manage your Moonlit or Moonshadowed debuff, then stand near the orb to avoid Lunar Halo.
Antitwilight
Roomwide AoE
Deals damage to all party members andreturns the arena to normal.
Dance of the Dead
Lunacy
Continuous Stack Marker
Targets one player with acontinuous Stack Marker. Group up on the affected player andstay there for the duration of the attackto spread out its damage. The Healers shouldheal through this attackto keep everyone healthy.
Dark Blade/Light Blade
Deals damage in alarge conal AoE. Move to the opposite side to avoid the AoE.
Tsukuyomi will useNightfallthroughout this phase. If Nightfall triggersLead of the Underworld, the targeted player should try tostand on the border between both halves of the arenaso that everyone cangroup up for the Stack Markerwhile still being able to swap sides if needed.
These phase three mechanics will be repeated until Tsukuyomi is defeated. Pay close attention to yourMoonlitandMoonshadoweddebuffs and move as necessary to avoidDoom. A moon will also appear above your head during this mechanic that will fill up as your stacks increase. Use this to keep an eye on your debuffs.
