Extreme Vessel (極論の器, Kyokuron no Utsuwa) is an optional boss in Persona 4.
Extreme Vessel is found on the last floor of Secret Laboratory and appears after the sixth of October. It does not have to be fought in order to proceed in the storyline. Defeating it grants a boost to the protagonist's Courage stat and the Algernon weapon for Naoto Shirogane.
When starting the fight, the shadow will always use Virus Wave. Since this shadow doesn't take much damage from an all-out attack, it is advised to avoid doing it, in stead using the the fact that the damage received from a downed shadow is increased by using, for example, a Power-Charged Cruel Attack. This shadow tends to use buffs (Mind Charge, Power Charge and Rebellion ), so it is suggested to use Makarakarn, especially as most of the party members are weak to one magic, and Tetrakarn on the protagonist (as it using a Mind Charged Ma-dyne spell usually results in a one-hit party kill ). It won't always use a magic/ physical attack after respectively Mind Charge/ Power Charge (usually using, for example, Magarudyne two turns after using Mind Carge).
The stats for Extreme Vessel applies for both Persona 4 and Persona 4 Golden.
|Storyline||Shadow Yosuke - Shadow Chie - Shadow Yukiko - Shadow Kanji - Shadow Rise - Shadow Teddie - Shadow Mitsuo - Shadow Naoto - Kunino-sagiri - Tohru Adachi & Magatsu-Izanagi - Ameno-sagiri - Kusumi-no-Okami * - Izanami - Izanami-no-Okami|
|Sub||Avenger Knight - Daring Gigas - Amorous Snake - Killing Hand - Dominating Machine - World Balance - Chaos Fuzz - Envious Giant - Neo Minotaur - Sleeping Table|
|Extra||Contrarian King - Intolerant Officer - Momentary Child - Escapist Soldier - Extreme Vessel - Lost Okina|
|Other||Margaret - Reaper|