Eiha

Eiha is Joker's Side Special Move. He casts a skill which can do continuous damage, similar to a poison effect.

Eiha
Joker will snap his finger to cast an Eiha spell that travels a bit of distance. If an opponent gets hit with it, they will receive very minimal knockback and damage, but they also get continuous damage for a while. The fighters affected by Eiha has a "shocked eye" effect.

Eigaon
If Joker has his Persona with him, Arsene will cast an Eigaon spell instead, which has a larger hitbox, travels faster and will stay a bit longer on the ground before disappearing. The affected players will receive multi-hit damage, followed by a much higher rate of continuous damage for an extended period of time.

Origin
In Persona 5, Eiha and Eigaon are both Curse-type magic skills. They do light and heavy Curse damage to one enemy respectively.