Yeah, it's Polar Night Tower, Water/Dark is going to absolutely suck.
Tower of Flare wasn't much a hurdle for me tbh, at least not until the last stage but I was prepared with the Siren ult helper, I knew there was no way in hell I could outdamage the Ifrit's 35k defenses so I just outlasted him instead.
Next major hurdle should be the Leviathan though, which is going to suck since I'll need to stack 373k damage in five turns (8 if I can use echidna) and I don't think even with double Firedragon Tyrannos I can do that much in a single burst, maybe with FFanatic's TAMADRAPurin since that's x7 multiplier but that would mean I need to stack 53355 damage which is still going to be hard as balls, unless I get somehow really frickin' lucky with heart orbs and fire orbs for Rowdy Samurai's orbchanging and Horus's enhancement, would be nice if I could get Tyrannos's 1,3x multiplier going too.
Hell, even if the stars align and I can get FFanatic's TAMADRAPurin -and- my Tyrannos's ability up by the time I reach the boss (since I'll be having to kill stuff before they kill me to survive) I'll still need to stack 40316 damage in one go to OHK the Leviathan, which is still going to be ass, and that number unfortunately does already account for the damage Magma Breath will deal. Hell, considering my team has a combined ATK score of 4214 I'll need to make a x9,5-ish multiplier out of orbs, enhancements and combos alone, that is going to suck.
And that's even assuming I can get to the leviathan in the first place.