You will encounter Fionn mac Cumhaill when you make your way to Da’at Shinagawa’s Konan 2nd Block for the first time in Shin Megami Tensei 5 Vengeance. He will attack when you try to cross the bridge from Mitatebashi.
He is one of the main story bosses like Nuwa for both the Canon and Creation and Canon of Vengeance, and you will need to defeat him to continue with the story.
Fionn mac Cumhaill excels at dealing Physical, Ice, and Fire damage. Hence, based on the type of party you are running, you might either struggle or find it comparatively more manageable to beat him.
Fionn mac Cumhaill Weakness and Resistance in Shin Megami Tensei 5 Vengeance
Fionn’s Elemental Weaknesses and Resistances
| Element | Resistance/Weakness |
|---|---|
 Physical | – |
 Fire | Block |
 Ice | – |
 Electric | Weak |
 Force | – |
 Light | Block |
 Dark | – |
Fionn mac Cumhaill Status Ailments Resistances
| Status Effect | Resistance/Weakness |
|---|---|
 Sleep | Block |
 Confuse | Resist |
 Charm | Resist |
 Mirage | Resist |
 Seal | Block |
 Poison | Resist |
Fionn mac Cumhaill Skill Proficiencies in Shin Megami Tensei 5 Vengeance
Elemental
| Element | Proficiency |
|---|---|
| Physical | +5 |
| Fire | +4 |
| Ice | +3 |
| Electric | -6 |
| Force | – |
| Light | – |
| Dark | – |
Other Statuses
| Status | Proficiency |
|---|---|
 Almighty | – |
 Ailment | – |
 Recovery | – |
 Support | – |
Fionn mac Cumhaill skills in Shin Megami Tensei 5 Vengeance
Healing Hands (Innate Skill):
- When restoring an ally’s HP, ailments may be cured
Mac an Luin (+5):
- (Unique) Severe Physical attack to 1 foe. Great effect if Critical
Dark Sword (+5):
- 2 medium Physical attacks to 1 foe. Chance of inflicting Seal.
Pierce Armor (+5):
- Weak Physical attack to 1 foe. Lowers Defence by 1 rank for 3 turns.
Bufula (+3):
- Medium Ice attack to 1 foe
Maragion (+4):
- Medium Fire attack to all foes
Tarukaja:
- Raises Attack of 1 ally by 1 rank for 3 turns
Omagatoki Critical:
- All attacks, including magical attacks, will become Critical hits for all allies for 1 turn.
How to beat Fionn mac Cumhaill in Shin Megami Tensei 5 Vengeance
1) Make sure to have Phy and Fire Dampeners in your inventory
If you aren’t careful, Fionn will be able to one-shot your entire party after charging Magatsuhi. So keep Physical Dampeners as well as Fire Dampeners to be able to block his attacks during Omagatoki: Critical and waste his press turns.
While you will be able to buy Fire Dampeners from Gustave, Physical Dampeners are a different story altogether. You will be able to acquire them by either beating enemies, through treasure chests or by interacting with Quest Navigator points of interest. There is a fair bit of RNG involved when acquiring physical Dampeners.
Additionally, some side quests will offer Physical Dampeners as well. Missions like “Roar of Hatred” will provide you with the item.
If you do not have any Phy Dampeners use a Fire Dampener and then make your party guard. That’s the only way of surviving his Omagatoki: Critical.
2) Keep a lot of buffers and debuffers in the team
A good way to make the fight considerably easier is to use demons that have a lot of -kaja and -nda skills. Fionn comes with Tarukaja which will increase his ATK. The higher his damage gets the easier will he find it to one-shot the Nahobino with Mac and Luin.
Hence the goal will be to have a demon with Tarunda to reduce his attack and also have a demon with Sukunda and Sukukaja to make it difficult for him to land hits on you. If Fionn misses his attacks it will burn through his press turns.
3) Have demons with strong Elec skills
Fionn is weak to Elec skills and to deal consistent damage to him you will need to have demons that come with Zionga and good Elec affinity. Fionn has a lot of HP that you will need to get through, and by continuing your press turns you will be able to deal a consistent amount of damage to him during your turn.
Best demons to beat Fionn mac Cumhaill in Shin Megami Tensei 5 Vengeance
Best Support:
- Jatayu
- Anahita
- Kelpie
- Tao (Canon of Vengeance)
- Yoko (Canon of Vengeance)
With the right fusion paths Jatayu, Anahita, and Kelpie will come with some great -kaja and -nda skills. However, do keep in mind that Anahita is weak to fire, and Fionn will be able to use her to extend his press turns.
If you are playing the Canon of Vengeance narrative you will have access to both Tao and Yoko. Yoko has Matarunda which will lower Fionn’s attack while Tao has Marakukaja which will increase the defense of all active party members.
Best Healers
- Hariti
- Kelpie
- Anahita
- Principality
- Tao (Canon of Vengeance)
These demons come with Diarama which will provide a significant HP recovery for demons in your party. For Canon of Vengeance, you will have Tao who has Media and will heal all active party members at the same time.
Best DPS
- Mothman
- Lilim
- Setanta
- Nahobino
- Yoko (Canon of Vengeance)
For the Elec demons, it’s best to go with Mothman and Lilim. They both have Zionga and positive Elec affinity. Additionally, if you are using Nahobino as a mage then you will have access to Ruinous Thunder from an Aogami Husk by now. Essence fuse the skill onto them and the Nahobino will be able to melt through Fionn.
For Physical DPS you can use Stanta and the Nahobino. They will be able to take out massive chunks of Fionn’s HP after activating Omagatoki: Critical.
For Canon of Vengeance, you will have Yoko with Zionga who can help extend your press turns.
After you beat Fionn mac Cumhaill you will be able to continue the narrative into Konan 2nd Block in Atlus‘ RPG.
