Boss Guide: Ch17-2 (Gotterdammerung)

• The fight against Gotterdammerung Lostbelt’s Tree of Emptiness, Sombrero, is a fight defined by the boss’s gimmick of continuously stacking debuffs and buffs. The Caster-class Tree comes with 3 HP bars, and starts off with two unremovable buffs which will continuously apply an NP gain debuff as well as a HP Recovery Effectiveness debuff to all active party members at the end of every turn. Each debuff will generally stack to a maximum of 3 (after which the earliest debuff will expire due to their 3-turn duration).
• Upon first Break, Sombrero stops applying the NP gain debuffs, as the continuous buff is replaced by another unremovable buff which applies a Defense buff to Sombrero itself every turn. Likewise, the HP Recovery Effectiveness debuff gimmick is removed at the second Break, replaced by an unremovable buff which applies an Attack buff. Similarly, both buff types last for 3 turns and will therefore stack to up to 3 times.
• Sombrero comes with two additional active skills. The first applies a great reduction to a party member’s NP gain for 3 turns (yes, it stacks with his continuous debuffs), while the second will decrease the amount of available critical stars by 10. Lastly, its NP removes all defensive buffs (including Defense Up, Evasion, and Invincibility) though this effect is thankfully only activated after the damage (meaning that having Evasion/Invincibility will still block the NP damage).
• In essence, the early fight can be described as an arduous battle where Sombrero tries to wear the Chaldean party through slow attrition, while the latter part of the stage is a damage race with an emphasis on sustained damage output. 
• While the boss itself doesn’t hit that hard towards Riders (at least until its final HP bar), Sombrero’s overall tankiness means that it will be able to unleash multiple NPs over the course of the fight, making it the primary threat of the stage. Ideally, its NPs should be defended against by use of party-wide Invincibility or Evasion.
• Generally speaking, it is best to try and burst through Sombrero’s first HP bar, as its NP Gain and HP Recovery Effectiveness debuffs will shut down most compositions focusing on long-term sustain.
• As the fight progresses, it becomes a question of depleting Sombrero’s health through his stacked Defense buffs. The Chaldean party will still have to deal with essentially nonexistent healing throughout the second HP bar, as well as greatly increased boss damage after transitioning into the final bar.

• Rider-class damage dealers fare best against this boss, particularly those with Defense Ignore, as well as buff/debuff removals to deal with the stage’s gimmicks. Riders who have a personal hard defensive skill will also hold an advantage over other options. 
• Ivan the Terrible in particular is known for being able to solo the stage, as are Martha and Ushiwakamaru, though the latter two may require additional investment such as Grailing or higher NP level.
• Attack buff skills can also be used to bypass the boss’s Defense buffs to an extent due to additive stacking (Defense buffs are calculated identically to Attack debuffs), so Riders with easy access to these buffs (such as Ozymandias) are recommended. Having high Debuff Resistance (Quetzalcoatl, Martha) will also help with this stage.
• In lieu of the above, Sherlock Holmes is a very powerful option for this stage thanks to his Defense Ignore buff. 
• Jeanne d’Arc is a must for any sustain-oriented team, as her reliable debuff removal and Invincibility works great against the stage’s gimmicks. She may however need some support in terms of NP Charge (which can in part be helped with Prisma Cosmos).
• Either the Atlas Academy Uniform or Mystic Code: Chaldea should be used for this stage, with the former providing a way to remove debuffs, and the latter granting extra sustain and burst damage.

In terms of CEs, The Infant of Atlas Craft Essence may also be employed similarly to Holmes. Alternatively, Origin Bullet is always a powerful choice outside of hybrid Starting NP Gauge CEs (e.g. Golden Sumo).

• Note that these videos are not affiliated with GamePress, but showcase some lineups that are effective in clearing the final challenge. These can serve as a good reference for how to rotate skills during this quest or simply to have a look at the encounter before diving in.
  • Ivan the Terrible solo
  • Ushiwakamaru (level 100) solo
  • Saint Martha (NP3) solo
  • Ushiwakamaru ft. Sherlock Holmes