A more helpful guide to the Remuru fight might be nice, phase 2 seems numerically impossible at level 22. There must be some gimmick I'm missing, but then again, phase 1 is also entirely RNG because one missed shield bash is instant death. I know about the damage reflection and the heal blocking, but that doesn't help at all. Even without the heal blocking, he nukes 85% of my HP with one hit. So anyone getting hit twice instantly dies, and there's no way to heal up in time even if I cleanse the debuff immediately either, since there's no way to full heal the whole party every turn. I feel like there should be a warning that you need to be well over level 25 to even attempt this fight, very odd for it to be story progress locked too, this is just outright impossible without halting the pacing of the game for several hours to grind levels mindlessly. I'm also now in a position where I would be completely softlocked if I didn't habitually save in multiple slots, since there is no way to leave the castle and no way to beat Remuru at this level, and no way to grind levels in the castle.
Viewing post in Player's Guide Link. FAQ up top.
Use the bell in your key items to leave the castle. As for killing the boss, if you don't manage to do it with the strategy listed in the guide, here's an alternative one that's more or less just unga bunga. Requires some baby making to get enough points for learning skills.
A list of requirements:
Elucia skills learned - Hero Strike, Masochism, Resilience, and extra armament so she can equip double Nail Ornament, or double Sword Amulet.
Marie skills learned - Amplify, you don't need anything else.
Ran doesn't need anything.
As for setup of the actual strategy.
Turn 1 Marie and Ran need to go first. Ran uses a Euphoric Seed on Elucia. Marie uses Amplify on Elucia. Elucia uses Hero strike. Then for phase 2, Ran uses a single target momo to give Elucia 2 MP, Marie uses Amplify on Elucia again, and Elucia uses Hero Strike.
Results depend on how high you can get Elucia's attack.
Euphoric Seeds are sold at Altomyostr for 50 medals. If done properly, just 1 should be enough for both Phase 1 and 2 since it lasts 3 turns.
The strategy more or less focuses on just killing the boss in 1 hit, and since Elucia has a passive that prevents her from dying, she won't die on phase 2 despite taking a huge amount of damage from herself.
If you find you can't get your atk values up high enough with chroma alone, grind brothel more and unlock the stat level up in the church and raise atk for Elucia. Example below.
Phase 1 isn't too bad, Ran has a skill that AT advances someone and gives them true strike, so you can just use that and shield bash alternatingly to guarantee a stunlock. (I just didn't have enough MP to do this turn 1 without some MP healing items, but I can go grind out the starting MP passives).
I don't think killing the boss in one hit is remotely possible for me lol. I put up all the buffs I could and hero strike doesn't even take off 10% in phase 2, then he kills a party member and puts another at critical HP (or puts the entire party at critical HP with the healing debuff). I'm trying to do this right when it unlocks at level 20 so that's not even close to possible. Guess I'll just go grind out all my skills and 20 more levels or so. The fact that it warns you about the timer made me assume it was balanced for doing it right after you get Ran, when clearly it's balanced as endgame content and I'm here way too early
Assuming you followed all instructions correctly, it should be possible to 1 shot at level 10-15. If you only did 10%, it sounds like you weren't using the strategy.
Basically the way Elucia's skills work if you learned all the required skills:
Elucia gains a damage buff the lower her hp is. Euphoric seed reduces her HP to 1 and gives her crit and atk buff thus maximizing the buff. Amplify basically doubles her damage. Then Hero Strike does massive damage because not only does it have a high damage value, but it completely ignores enemy defense.
The boss only takes a turn after all 3 characters have taken one, so if it gets a turn, you did it wrong.
Although I did forget that the MP passives were a thing, but yeah you need those on Elucia too. You also probably need them on Marie to be able to use Amplify 2x in a row.
Hero strike is a really strong skill, even without Ran, and just having Amplify on Marie, I could 1 shot Belobog the superboss in the forest at level 5, and that was way before unlocking the nun upgrade station to boost Elucia's attack.