Fusion accidents are a hazard that can occur during demon fusion. This can either result in the loss of all component demons, or may result in something unexpected. Some races of demons can only be obtained via fusion accidents, often under specific circumstances.
- Shin Megami Tensei II
- Shin Megami Tensei: if...
- Shin Megami Tensei III: Nocturne
- Shin Megami Tensei: Strange Journey
- Shin Megami Tensei IV
- Devil Summoner: Soul Hackers
- Devil Summoner: Raidou Kuzunoha vs. The Soulless Army
- Devil Summoner 2: Raidou Kuzunoha vs. King Abaddon
- Megami Ibunroku Persona
Shin Megami Tensei II
There is a rare chance that a fusion accident will happen, resulting in a different demon.
Shin Megami Tensei III: Nocturne
There is always a low chance of it happening with regular fusion; however, the odds of fusion accidents greatly increase in Full Kagutsuchi phases, though Special Fusions and Fiend Fusions are immune.
Shin Megami Tensei: Strange Journey
A fusion accident chances of happening increase with the Copernicus sub app, while Fracastoro prevents it. Using Copernicus with Zealot Summons increases the chances of getting a Zealot demon.
Shin Megami Tensei IV
Generally, the chance of a fusion accident occurring is low (1/64), but fusing dead (0 HP) and/or Foul demons will increase the odds - each dead demon used increases the chance by 1/64, while including a Foul doubles the final chance, for a maximum chance of 6/64. When a fusion accident occurs, the result is typically within ~5 levels of what the normal result would have been, and the skill repertoire of the resultant demon is randomly selected from its default skills and its components' skills, except those of the Famed race, which are guaranteed to have their default skills. Most Famed race demons can only be created via fusion accident.
Devil Summoner: Raidou Kuzunoha vs. The Soulless Army
A fusion accident in this game will result in one of five different types of Legion demon.
Devil Summoner 2: Raidou Kuzunoha vs. King Abaddon
When fusion accidents occur it will become one of three demons: Fury Order Slime, Skill Order Blob, or Frost Order Black Ooze. If one attempts Fiend Fever or Evil Fever fusion and have all the demons of those orders on them, then one of the three slime demons will then be the result.
Megami Ibunroku Persona
Personas of the Fool Arcana can only be created through Fusion accidents. The other possible results are that the persona will be chosen at random from a different arcana, the persona will gain or lose stats, or will randomly inherit a skill from one of its "parents".
To guarantee a fusion accident resulting in a Fool Arcana persona, the player can take 101 or 230 steps from a "hard reset" (as in, not already mid-game and loading a save or selecting "Return to Title;" the player must exit the game to reset the) in an area where no enemies will attack, such as the Mikage Sun Mall (for an odd number of steps) or the Black Market (for an even number of steps), and performing a White Fusion, or by taking 275 or 546 steps and performing a Red Fusion. As the lowest level Fool is level 30, the protagonist must first be at least level 25.
A fusion accident resulting in +2 to all stats can be guaranteed by taking 6 or 25 steps and performing a White Fusion, and a random skill inheritance accident can be guaranteed by taking 31 or 62 steps with a White Fusion or 21 steps with a Red Fusion.
Note that, during the Snow Queen Quest, steps inside the infirmary count towards the number of steps for forcing a fusion accident. As such, it is possible to do any of the confirmed accidents since the player can take one or two steps prior to leaving the infirmary, allowing both even and odd step fusion accidents.
Also note that this works when using Totems and Gems, but not Skill Tablets or Items, so any extra skills wanted on the end result must be from inheritance. As Skill Inheritance functions as normal, it is likely that Unknown Powers do as well.