【FGO】Lostbelt: Beast IV/Koyanskaya Boss Fight ft Taikoubou/Melusine - Tunguska Sanctuary Event

Whenever Nasu is involved with a Boss fight, you know bad things are gonna happen.
I made a big misplay on Turn 5, nearly killing my team by using Taikoubou's NP when the Ruler HWB-M8 was still alive. Do try to avoid doing that.
Will try to 4T this but the Debuff success rate down gimmick kinda killed my motivation.

Gimmicks:
Black Barrel and Orochi gimmick are available, as usual.
Every Servant will get a 1 time Guts of 60% HP.
Beast IV will decrease the Buff success rate of every ally and enemies on the field.
To somewhat counter this, NPC Taikoubou is available to use. While on field, he will increase buff success rate and negate defensive disadvantage against Beast IV for all allies.
Keep in mind that there is still a small chance your buff will fail even with NPC Taikoubou on field.
Both Servant's death and her creature's death will heal her by 50k HP each.
She's accompanied by 2 of her creatures on every HP bar.
If her creatures are still alive when you break her current HP bar, she will kill them before summoning the next 2.
Each creature has a field effect.
Cerberus field effect will grant all its allies 2 hits Invulnerability every turn.
The most dangerous field effect is from the Ruler HWB-M8 that she summoned on her last HP bar. If you hit any other target aside from it while it's still alive (including with AoE), it will inflict Instant Kill to your whole team.
There are like a dozen more gimmicks that I didn't list here.

Tbh just pick a Tamamo support and solo the fight to save you some pain.

#fgo