I think this a great idea for a perk, hopefully the devs see this, and for anyone who would claim its op, you can already make alot of op builds, example nimble, duelist, dodge, killing frenz combo but they are only really op in certain situations, just like this would be, which brings good balance. Plus its not that easy to get potions so that would limit its opnes also. I think it would fit perfectly, just make it a higher teir perk like lvl 6 plus.