Almighty Skills

Almighty spells carry a special powerful non-elemental property, and is generally unstoppable.

General
Megido is a shortened spelling of Megiddo. Har Megido (Mount Megiddo) is the place described in the Bible where Armageddon will take place.

Zan Family

 * In Persona 2, Zan spells do Almighty elemental damage; Mazan spells were omitted.

Gry Family
In Persona 2, Gry was a group-damage almighty elemental family.

Shin Megami Tensei Nocturne Specific

 * Skills unique to Shin Megami Tensei III: Nocturne.

Digital Devil Saga: Avatar Tuner Specific

 * Skills unique to Digital Devil Saga: Avatar Tuner.

Devil Survivor Specific

 * Skills unique to Devil Survivor.

Soul Hackers Specific

 * Skills unique to Devil Summoner: Soul Hackers.

Strange Journey Specific

 * Skills unique to Shin Megami Tensei: Strange Journey