There are many special achievements in "Call of Duty: Black Ops 6", and quick reflexes is one of them. If you want to achieve this achievement, you can use an adrenaline stimulant in the campaign to cause 5 head injuries. It will cause partial damage, so you just need to pay attention to it when fighting.
How to obtain the Quick Reflex achievement in Call of Duty 21 Black Ops 6
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A single use of Adrenaline Stimulant can cause 5 head injuries in the campaign
Halfway through "High Rollers" you will take back control of Case and fight inside the casino. Just before the enemy Shield Elite appears, there will be a hideout to your left before the turn. Check the stash for a separate Adrenaline Shot and be ready to use it on the enemies coming down the stairs and around the pillars. Don't try to kill the shields, they take a long time to kill with a head shot. Remember, you can also move around during this time, so if you can't see because of screen distortion, get closer if you need to.
