In today's episode, we go through the newly renovated Winter Forest to get to Hakugyokurou! As long as you bring Barettes on everyone, you should be just fine. In addition, bringing Patchouli with a Barette will make you night invincible, as the only things that'll hurt her are physical attacks, or the Half-Phantom.
Enemies:
Tundra Turtle: Not a very difficult enemy, as it mainly sticks to physical attacks.
Tundra Scorpion: Likewise, this enemy will mainly stick to physical attacks.
Snow Beast: Without Barettes, this enemy is pretty dangerous, especially if they show up in groups of 4. They will often use either Blizzara or Ice Storm, which will do quite a bit of damage to the party.
Lost Soul: These enemies don't really do much on their own other than use physical attacks or Drain. However, leave them alone for about 5-10 turns, and they transform into Half-Phantoms.
Frozen Toad: A very rare enemy, but very powerful, moreso than the Half-Phantom. They have HP Apples to steal, but at a 5% chance and they flee after about 20 turns. They have access to powerful Ice spells such as Freeze and Blizzaja, so even with a Barette, most characters are going to die fast.
Half-Phantom: The Notorious monster of the area. They are different from other enemies in that they don't use a single Ice-elemental attack, and instead use Ghost/Shadow-elemental attacks. They do drop the rare Youkai Sword "Inubashiri", so they're worth to fight at least to get those!
Bosses:
Ice Behemoth: The boss uses powerful Ice-elemental spells and attacks, and that's it. Bring Patchouli + Barette, and she's pretty much invincible against him. Other characters can survive decently with a Barette, so Ice Behemoth is far from being a tough boss at all.