For this you'll need to defeat Gargos while removing none or only one of his buffs.
For more tips on how to defeat here, I recommend reading my solution for
Here is the list of Gargos buffs, so you can "choose" which ones are "better" for him to have, depending on your fighting style.
- Fang of Gargos: Damage Increase
- Heart of Gargos: Health Regeneration
- Veins of gargos: Instinct meter drain
- Flesh of gargos: Increased max health
- Blood of gargos: Shadow meter regeneration
- Lungs of gargos: Shadow meter drain
- Wings of gargos: Bonus potential damage
- Spirit of gargos: Extended instinct mode
- Eye of gargos: Party incoming attacks
- Claw of gargos: Full damage on blocked attacks
When he gets to the revive phase (more than 50% of instinct), it is very important that you hit him with a heavy attack as soon as he starts the process. This way, you will have less health to deal with.