Eiha / Eigaon
When activated, Joker snaps his fingers, and sends out a small projectile with an explosive area of effect. The projectile doesn't do much damage, but will cause the opponent to become cursed, taking damage over time. It can also be used to situationally start combos or escape disadvantageous situations thanks to its favorable launch angle.
If Arsène is currently out when the move is used, Joker instead uses Eigaon, a more powerful projectile that hits multiple times, and causes the curse to deal more damage and do so more frequently, but last slightly less time. It will also explode and leave a "pillar" of energy that maintains the multihit hitbox if it hits the floor, allowing it to be used for area control by the player. This is especially helpful if the opponent is on the ledge, although it is a committal option in this situation. The "pillar" can also block weaker projectiles, giving it some minor defensive utility.
The damage taken from the curse is as follows.
Eiha is a Death element Persona skill first appearing in Revelations: Persona. It reappears as a Curse element skill in Persona 5, while Eigaon makes its debut in the same game. Eiha is the basic form of the attack, while Eigaon is the most powerful single-target form. Notably, in Persona 5, Arsène begins with Eiha but cannot normally learn Eigaon; however, Arsène has access to it in the first battle done in the prologue (which takes place in the halfway of the story) and can inherit it from other Personas. Arsène also learns it in the spin-off game Persona Q2: New Cinema Labyrinth. In Persona 5 Strikers, Arsène can also learn Maeigaon, a variation of Eigaon that hits all enemies (or in the case of Strikers, hits a wider area of enemies) upon reaching Level 62.
The smoggy red, black, and purple effects are based off Eiha and Eigaon's appearance in Persona 5, complete with Eigaon's swirling vortex and grinning face.
During the animation for both attacks, a blue flame effect appears around Joker's feet (the same as Rebel's Guard), based off the aura that appears when the Phantom Thieves are selecting and casting a Persona skill in Persona 5. Joker's finger snap when using this attack harkens back to his animation in Persona 5 when using an item in battle, while his kneeling down when casting Eigaon resembles Arsène's magic attack animation in the same game.
The lingering damage effect is not present in Persona 5, though it may be a reference to Eiha and other Death spells' attributes in Revelations: Persona, where they deal persistent damage to the targeted enemy over the course of several turns.
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