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Shin Megami Tensei’s staple mechanic that offers a massive level of creativity in building your party, Demon Fusion, returns inShin Megami Tensei V: Vengeance. Combining your various mythological creatures together and forming new additions to your compendium has been tried and true for decades… mostly.
Since early Megami Tensei, a small quirk may appear when fusing demons that causes an unexpected outcome. The expected fusion result may instead transform into a wildly different demon than what was promised. In Vengeance, this mechanic can be manipulated to create demons far above your current level, or even to fuse some of the franchise’s newest demon allies.

When Do Fusion Accidents Happen?
First off,fusion accidents are more likely to occur during a full moon;when the Moon Phase in the top left corner of the screen reads “Full”.
Secondly, a new Miracle added to SMT V: Vengeance called"Mutative Element" can increase the chances of fusion accidents taking place.Stacking these two factors will set the fusion accident rate to be around 40 percent.

Moon Phases aren’t determined by time passing, but ratherby the amount of steps taken. If you need to cycle phases to get to “Full”, simply run around in the overworld while checking the phase. This is a great time to farm materials from vending machines to sell for money, as you can instantly teleport back to the Leyline Fountain when the moon is full.
Why Are Fusion Accidents Beneficial?
Demons created via fusion accidents are wildly inconsistent in both level and race, meaning that powerful, high-level demons can be fused much earlier than they would be through normal fusion methods.
For example, testing fusion accidents resulted in creatingYoshitsune, a very powerful ally, almost ten levels under the normal level requirementwithout using any of the standard demon races that are able to fuse into it.

As is the case with fusing any demon, ones created through mistakesalso inherit the chosen skills from both ingredientsand allow the user to pass on rare or powerful skills to their new creations.
The amount of inherited skills given to fusion accident demons is based on the number of innately empty skill slots that the new demon has, so choose a general set of powerful skills when purposefully triggering accidents, as not all skills may transfer over.

What Can Be Created With Fusion Accidents?
Any demon of any level may be created upon triggering a Fusion Accident, but it is exceedingly rare to see those not within ten levels of yourself.With Vengeance’s release, there are even some brand new demons, both to SMT V and the franchise as a whole that can only be created via fusion accidents.
These demons include Hare of Inaba, Amabie, and Kinmamon. Creating them is unrelated to the sidequest that each of them can give to you in the overworld and isthe only way to recruit them to your party.
There are no special instructions for making them outside of pure luck. You’re unlikely to fuse them without farming through many other random results. However, there are some methods to ensure that your chances of acquiring them are the best they can be.
The Best Way To Cause Fusion Accidents
To set yourself up for a session of farming fusion accidents,a few steps must be taken. First, and most importantly,ensure that the moon phase shows “Full”. A unique noise will play in the overworldwhen the phase transitions to full, and the World of Shadows will play an alternate music track.
Do note that the “New” Moon Phase will play the same music, but doesn’t seem to boost the rate of fusion accidents.
Next, it’s highly recommended to purchase the “Mutative Element” Miracle for 100 Glory, which also boosts the rate of fusion accidents triggering.This Miracle can be bought after defeating an Abscess in the Yurakucho area.
With enough luck, you’ll begin to make demons far above your level and greatly buff your party’s overall deadliness.