Calculate demon fusions, inherited skills, and find the perfect combinations for your journey through the Vortex World.
Fusion Calculator
Demon 1
Demon 2
Special Conditions
Fusion Result
Inherited Skills
Stats
Affinities
Stats Comparison
Race Compatibility
80%
65%
45%
90%
Popular Fusions
Pixie + Angel
Result: Unicorn
Black Frost + Jack Frost
Result: Trumpeter
Daisoujou + Matador
Result: Alice
Thor + Norn
Result: Metatron
This Shin Megami Tensei III: Nocturne Fusion Calculator is a fan-made tool and is not affiliated with Atlus or SEGA.
Shin Megami Tensei III Fusion Calculator: Mastering Demon Fusion
In the dark, post-apocalyptic world of Shin Megami Tensei III: Nocturne, the demon fusion system stands as one of the most complex and rewarding mechanics for players to master. This comprehensive guide explores the intricacies of Kagutsuchi’s phases, demon alignment, and strategic fusion combinations through detailed explanations, visual demonstrations, and practical examples.
Understanding the Fusion System
The fusion calculator in Shin Megami Tensei III serves as an essential tool for players looking to optimize their demon collection and create powerful allies for the challenges ahead. Unlike simpler combination systems, SMT III’s demon fusion follows moon phase-based rules, complex inheritance patterns, and special fusion recipes that require strategic planning to execute effectively.
This guide will break down each component of the fusion system, from basic two-demon fusions to complex multi-demon special fusions, providing you with the knowledge needed to create powerful demons tailored to overcome the game’s formidable challenges.
Fusion Mechanics and Principles
Kagutsuchi’s Phases
The foundation of demon fusion in SMT III lies in the Kagutsuchi system. This moon-like entity cycles through phases that directly impact fusion results, skill inheritance, and demon levels.
Fusion Types
Shin Megami Tensei III features several fusion types, each with unique rules and outcomes:
Normal Fusion
Combining two demons to create a new demon based on level averages and moon phases.
Triangle Fusion
Using three demons to create more powerful results with enhanced skill inheritance.
Special Fusion
Specific demon combinations that yield unique, powerful results regardless of level.
Moon Phase Fusion
Fusions that are only possible during specific Kagutsuchi phases.
Level Calculation and Skill Inheritance
When fusing demons, the resulting demon’s level and skills are determined by complex formulas that consider the base demons’ levels, skills, alignments, and the current Kagutsuchi phase.
Fusion Level Calculation
Estimated Result Level
Skill Inheritance Patterns
When a demon is created through fusion, it inherits skills from its component demons. The inheritance follows specific patterns influenced by moon phases and demon alignments:
| Inheritance Type | Probability | Skill Selection | Optimal Phase |
|---|---|---|---|
| Random Inheritance | 60% | Skills chosen randomly from both parents | Crescent Moon |
| Skill Affinity Priority | 25% | Higher chance for skills matching demon’s affinity | Full Moon |
| Parent Priority | 10% | Skills primarily from higher-level parent | Half Moon |
| Fixed Inheritance | 5% | Specific skills always inherited | All Phases |
Advanced Fusion Strategies
Optimizing Skill Inheritance
Mastering skill inheritance is crucial for creating powerful demons that can overcome SMT III’s challenging battles. Here are advanced strategies for optimizing your fusion results:
Skill Inheritance Priority
Passive Skills
Always prioritize useful passive skills as they provide permanent benefits without MP cost.
Elemental Coverage
Ensure your demon has attacks covering multiple enemy weaknesses and resistances.
Healing & Support
Include at least one healing or support skill for battle sustainability.
Inheritance Blocking
Sometimes you want to prevent certain skills from being inherited. Use these techniques:
- Fill skill slots with desired skills before fusion
- Use skill-changing items to replace unwanted skills
- Fuse demons with complementary skill sets
- Take advantage of skill type affinities
Fusion Chain Optimization
Creating the ultimate demon often requires planning multiple fusions in sequence. This “fusion chain” approach allows you to transfer specific skills through intermediate demons to reach your desired result.
This fusion chain demonstrates how to create a versatile healing demon with both offensive holy attacks and defensive barriers by strategically combining demons with complementary skills.
Special and Ultimate Fusions
Special Fusion Recipes
Special fusions require specific demon combinations and often result in powerful, unique demons not available through normal fusion. These recipes remain constant throughout the game and are essential for completing your demon compendium.
| Result Demon | Race | Required Demons | Special Notes |
|---|---|---|---|
| Alice | Fiend | Nebiros, Belial | High-level dark skills |
| Shiva | Fury | Barong, Rangda | Requires specific story progression |
| Metatron | Seraph | Uriel, Raphael, Gabriel, Michael | All four Archangels |
| Beelzebub | Tyrant | Baal, Fly | Lord of the Flies transformation |
| Trumpeter | Fiend | White Rider, Red Rider, Black Rider, Pale Rider | All four Horsemen |
Moon Phase-Specific Fusions
Some fusions in SMT III are only possible during specific Kagutsuchi phases, adding an additional layer of strategy to demon collection:
Full Moon Exclusives
- Certain high-level demon fusions
- Enhanced skill inheritance rates
- Special elemental combinations
- Fiend creation possibilities
New Moon Restrictions
- Limited fusion options available
- Reduced skill inheritance quality
- Lower-level demon results
- Certain special fusions blocked
Fusion Formulas and Calculations
Mathematical Foundation of Demon Fusion
While demon fusion may seem like mystical art, it follows specific mathematical formulas that determine the level, stats, and skills of the resulting demon. Understanding these formulas can help you predict fusion outcomes more accurately.
Level Calculation Formula
Result Level = ⌊(D1 Level + D2 Level) / 2 × Moon Modifier⌋
Where D1 and D2 are the levels of the component demons, and the Moon Modifier ranges from 0.8 to 1.2 based on Kagutsuchi phase.
Stat Inheritance Formula
Stat = ⌊(D1 Stat + D2 Stat) / 2⌋ + Random(0, 3)
Each stat is calculated separately with a small random variance to add unpredictability to the fusion process.
Skill Inheritance Probability
The probability of a specific skill being inherited follows this formula:
P(skill) = Base Chance × Moon Phase Bonus × Affinity Multiplier
| Factor | Value Range | Description |
|---|---|---|
| Base Chance | 15-40% | Default probability based on skill rarity |
| Moon Phase Bonus | 0.5-2.0x | Multiplier based on Kagutsuchi phase |
| Affinity Multiplier | 0.5-1.5x | Bonus if skill matches demon’s elemental affinity |
Using Fusion Calculators Effectively
Advanced Calculator Features
Modern SMT III fusion calculators offer sophisticated features that can dramatically improve your fusion planning process. Understanding how to use these tools effectively can save hours of trial and error.
Reverse Fusion
Input your desired demon to see all possible fusion combinations that can create it.
Inheritance Prediction
See the probability of specific skills being inherited before performing the fusion.
Fusion Chains
Plan multi-step fusions to transfer specific skills through intermediate demons.
Maximizing Calculator Efficiency
Filter by Available Demons
Most calculators allow you to filter results based on demons you currently own, saving time searching for feasible fusions.
Set Skill Priorities
Advanced calculators let you prioritize specific skills, showing you fusion paths most likely to yield your desired skill set.
Save Fusion Plans
Many tools allow you to save complex fusion chains for later reference, perfect for long-term demon development.
Advanced Fusion Techniques
Skill Mutation and Optimization
Beyond basic inheritance, SMT III features advanced mechanics that allow for strategic skill optimization through specialized fusion techniques.
Skill Mutation
During certain fusions, skills can “mutate” into more powerful versions or completely different skills. This occurs randomly but can be influenced by:
- Kagutsuchi phases
- Demon race combinations
- Specific fusion combinations
- Story progression events
Stat Maximization
Through careful fusion planning, you can create demons with maximized stats:
- Fuse demons with high base stats in desired areas
- Use stat-boosting items before fusion
- Take advantage of growth spells during fusion
- Plan fusions around stat inheritance patterns
Fusion Accident Exploitation
Fusion accidents are random events where the fusion result differs from the expected outcome. While often frustrating, they can be exploited for benefit:
Increasing Accident Chance
- Fuse during specific Kagutsuchi phases
- Use demons with particular race combinations
- Fuse on specific calendar dates in-game
- Have low MAG reserves during fusion
Potential Benefits
- Unexpected powerful demons
- Rare skill combinations
- Higher level results than expected
- Unique demons not normally available
Conclusion: Mastering Demon Fusion
The Shin Megami Tensei III fusion system represents one of the most complex and rewarding mechanics in the Megami Tensei series. Mastering this system requires understanding Kagutsuchi phases, inheritance patterns, and strategic planning, but the payoff is immense—creating customized demons perfectly suited to overcome the game’s formidable challenges.
By utilizing fusion calculators effectively and applying the advanced techniques outlined in this guide, you can transform the seemingly random nature of demon fusion into a precise science. Whether you’re aiming to complete your demon compendium, create the ultimate battle demon, or simply optimize your team for specific encounters, the fusion system offers endless possibilities for customization and optimization.
Key Takeaways
- Understanding Kagutsuchi phases is fundamental to successful fusion
- Skill inheritance follows predictable patterns that can be manipulated
- Special fusions require specific recipes but yield powerful results
- Fusion calculators are essential tools for planning complex fusion chains
- Advanced techniques like skill mutation and accident exploitation can yield unique benefits
- Patience and experimentation are key to mastering the fusion system
As you continue your journey through the Vortex World, remember that demon fusion is not just a mechanic but an art form. Each fusion represents an opportunity to create something unique and powerful. With practice and the knowledge from this guide, you’ll be able to approach any fusion challenge with confidence and strategic insight, turning the dark power of Kagutsuchi to your advantage in creating the ultimate demonic allies.
Frequently Asked Questions
The Kagutsuchi system is fundamental to demon fusion in SMT III. Each phase of Kagutsuchi (New Moon, Crescent, Half, Full) affects fusion in different ways: Full Moon provides the best fusion results with higher-level demons and better skill inheritance, while New Moon restricts fusion options and reduces inheritance quality. The phase also determines which special fusions are available and influences the chance of fusion accidents. Planning your fusions around the Kagutsuchi cycle is essential for optimal results.
While you can’t directly control skill inheritance, you can influence it through several methods. Using demons with fewer skills increases the chance of desired skills being inherited. Skill-changing items can be used to replace unwanted skills before fusion. Additionally, some demons have affinities for certain skill types, making those skills more likely to be inherited when those demons are used in fusion. Fusing during Full Moon also increases the chance of better skill inheritance overall.
Triangle fusion (using three demons) typically results in higher-level demons with better stats compared to normal two-demon fusions. They also allow for more complex skill inheritance patterns, as skills can be drawn from three sources instead of two. However, triangle fusions require more resources and planning. They’re particularly useful for creating powerful demons in the mid to late game when you have access to a wider variety of demons and want to combine specific skills from multiple sources.
Most special fusion recipes are available from the beginning of the game, but require specific demons that may not be accessible until certain points in the story. Some special fusions are locked behind story progression or specific Kagutsuchi phases. Consulting a fusion calculator is the best way to identify when specific special fusions become available and what demons are required for them. The Cathedral of Shadows attendant will also provide hints about available special fusions.
The most effective way to use a fusion calculator is to work backward from your desired result. Identify the demon you want to create, then use the calculator’s reverse fusion feature to find all possible combinations. Filter results by demons you currently own, and look for fusion paths that maximize desired skill inheritance. For complex builds, use the fusion chain feature to plan multiple fusions in sequence to transfer specific skills through intermediate demons. Always account for the current Kagutsuchi phase in your planning.
Yes, some demons cannot be created through normal fusion and must be obtained through other means. Story-specific demons, certain boss demons, and some special event demons typically cannot be fused. Additionally, the Fiend race demons often have unique acquisition methods outside of normal fusion. DLC demons also usually cannot be fused and must be downloaded separately. Consulting a demon compendium or fusion calculator will show you which demons are fusion-only and which require alternative acquisition methods.
The levels of the demons used in fusion directly impact the level of the resulting demon. Higher-level component demons generally produce higher-level results. However, the relationship isn’t always straightforward—Kagutsuchi phase modifiers and specific fusion formulas can affect the final level. In some cases, fusing lower-level demons with high compatibility can produce better results than fusing higher-level demons with poor compatibility. The level calculation typically follows a weighted average formula with modifiers based on moon phase and demon race compatibility.
Duplicate demons can be valuable fusion material, especially if they have different skill sets. You can use them to create demons with customized skill combinations, or sacrifice them in triangle fusions. Some players keep duplicates with different skill specializations for different situations. Before fusing duplicates, consider registering them in the compendium if they have valuable skill sets you might want to access later. Duplicates with rare skills or high stats are particularly worth preserving in the compendium.

