Let me try to describe it again... remember brinkmanship is for completing a primary objective within 5 seconds of breaking disguise.
Create a freeplay round with custom settings (Friendly Fire on and min/max players 1 or 2).
I did it on Refuel because the place you have to hack is fairly safe and easy to see enemies coming, but any map where you have to hack something would work.
Start hacking the device, keeping an eye out for the enemy, when you see them, stop hacking and kill them. Once you get the hack percentage to 95ish, stop hacking and take a disguise.
Go over, break disguise, start hacking. It should only take a few seconds to finish and the trophy will pop.
Create a freeplay round with custom settings (Friendly Fire on and min/max players 1 or 2).
I did it on Refuel because the place you have to hack is fairly safe and easy to see enemies coming, but any map where you have to hack something would work.
Start hacking the device, keeping an eye out for the enemy, when you see them, stop hacking and kill them. Once you get the hack percentage to 95ish, stop hacking and take a disguise.
Go over, break disguise, start hacking. It should only take a few seconds to finish and the trophy will pop.