Hunter Instinct synergizes with the other oil talents. If you're using the right oil for the job, you'll deal 100% more critical damage against the targeted enemy type. So if you max out all three oil talents you'll have 50% more damage against the targeted enemy type, 25% more damage resistance when fighting that enemy and 100% more critical damage just by having the right oil on your sword. And you won't even have to worry that it will wear off.
Killing Spree will further increase your damage output. As long as your toxicity is above zero it will increase your critical hit chance by 50% each time you kill an enemy.
So all in all, these three talents will work much better with your build I think. They'll give you a ton of damage and critical hits and a bit of protection as well.
I thought Hunter Instict or Killing Spree was bugged and didn't work. I never read patch notes, so I have no idea if they fixed this or not. If I get rid of Quen's Exploding Shield then I feel like I should utilize an armor other than the Ursine armor. Should I use the Manticore armor in its place? This build does't really have a way to utilize adrenaline points hence why I was using Rage Management. I've also realized that grenades are kinda, sorta really fun. Is there a way to incorporate some explosives into this build?