Frost King is a boss from Etrian Odyssey 2 Untold and can only be fought by purchasing the DLC and accepting the "Winter's Harbinger" quest. He can be fought on the 18th Floor.
This massive, armored ice monster is responsible for freezing most of the 18th floor of the Petal Bridge, and must be slain by request of Canaan, who fears for the safety of his people, since the Bird Folk cannot handle the sudden weather change on their habitat. Similarly to the other DLC bosses, no backstory or origin is given to the Frost King.
As to be expected, this powerful beast controls ice at will, being able to even create a frost armor for himself, as well as being a formidable physical fighter, often attacking the party with powerful punches.
Despite its intimidating appearance, the fight against the Frost King is a very straightforward one, and he may be considered the easiest of the post-game bosses available in the game. A party of level 70+ characters is recommended before challenging this boss.
Preparations for this fight include a character that can use level 5 Ice Wall or higher, as well as items or skills that mitigate ice damage, such as Ice Mist and Frost Fantasia. Resistance against head bind and bash attacks can also help. Make sure to also bring powerful offensive characters, preferably with fire elemental skills.
At the beginning of the fight, the boss will follow a simple pattern of using Buster Arm, an attack that deals heavy damage to a single target and splash damage to the characters adjacent to it, followed by a normal attack, then repeating this cycle.
Once enough damage has been done to it, however, the creature will activate its Frost Armor. While this mode is active, the Frost King will be invulnerable to damage. On the turn after it activates the armor, the boss will use Crystal Scar, which removes all buffs from a single target and lowers their defense, and on the third turn after the frost armor has been activated, the boss will use the powerful Soul Freeze attack, which deals massive damage to random targets if the armor is still active when the skill is used, likely wiping your entire party. For that reason, it is imperative that you quickly destroy the armor. You can also use Perfect Defense once to block the attack if you are unable to destroy the armor in time. Even after the armor is destroyed, this attack will be very powerful, so using skills or items that lower damage from ice attacks is helpful in surviving it.
After the Frost Armor is destroyed for the first time, the Frost King's pattern will change. Now it will randomly use either a normal attack or Buster Arm, and every turn after it uses Buster Arm, the boss will use Avalanche, which deals massive ice elemental damage to the entire party, and is powerful enough to cause a wipe. Always use Ice wall on the turns this attack is going to be used. Also, do keep in mind that at the second time the boss uses his Frost Armor, he is guaranteed to use Avalanche on the turn between Crystal Scar and Soul Freeze, so stay on your guard.
Once the Frost Armor is defeated for the second time, the boss will gain access to Pile Bunker, which pierces across the character rows, dealing heavy damage and inflicting head bind. He will continue to use Avalanche on the turn after Buster Arm. Also, do keep in mind that if you take too long to defeat the Frost King in this phase, he may activate his Frost Armor a third time, so try to finish him off swiftly.
- Buster Arm (uses arms): Deals heavy damage to a single target and splash damage to adjacent characters.
- Avalanche (uses head): Deals massive ice damage to the entire party.
- Soul Freeze (uses head): Deals heavy Ice damage to random party members multiple times. Massive damage increases if the Ice Armor is active.
- Pile Bunker (uses arms): Deals heavy damage and pierces across both character lines. May inflict head bind.
- Crystal Scar (uses ???): Removes buffs and lowers defense power.
Conditional Drop Edit
In order to get his conditional drop, the Bound Ice Arm, you must defeat the Frost King while his arms is bound. Selling this to the shop unlocks the Arm Shield, which provides good ice resistance but creates a fire weakness in the user.