Shin Megami Tensei III: Nocturne
The Demi-fiend charges magical power in front of his face, before launching deadly beams from his eyes at a single enemy. It has the highest offensive power Demi-fiend can learn, and exerts unreasonable power when applying auxiliary magic. Because it is an Almighty-based physical skill, it is effective against all enemies and can be amplified by Focus.
Shin Megami Tensei IV Apocalypse
As before, Freikugel is exclusive to the Demi-fiend in the quest "Messiahs in the Diamond Realm." It deals heavy Almighty damage to a single target, and is complemented further by the Demi-fiend's passive skills Pierce and Almighty Pleroma.
Shin Megami Tensei V
Freikugel is no longer tied solely to the Demi-fiend, though it is part of his skillset during his boss fight as the final part of the Return of the True Demon DLC, with the skill animation from Shin Megami Tensei III: Nocturne returning. It is a severe-tier Almighty skill that runs off of the caster's Strength stat and has a high chance of getting a critical off of one target.
Made famous by the German opera Der Freischütz (The Freeshooter), the Freikugeln (singular Freikugel) were a set of magic bullets which never miss the shooter's target thanks to a deal with the devil. However, the devil would choose the final bullet's target.
After Shin Megami Tensei III: Nocturne, subsequent installments which introduce the same skill (至高の魔弾) which deals Gun-type (instead of Almighty-type) damage have the skill name localized as Riot Gun instead. The localization of Shin Megami Tensei IV: Apocalypse reintroduces "Freikugel" specifically for the Demi-fiend's unique skill which deals Almighty damage, to distinguish Riot Gun in the same game. This distinction via skill names is not present in the Japanese version of the game.