Just buy a Sager NP9873-S with Dual Nvidia 1080's in it and be done.
Gaming on a Macbook (even under Boot Camp) is just a joke at best unfortunately (unless you enjoy 10 year old games that is).
http://www.sagernotebook.com/Notebook-NP9873-S.html
Pretty! That thing is scary. lol.
Also, sorry Huntn but the OP wanted a PC. Macs simply are made with long outdated parts nowadays. While the PC world are on 1080s and such, Macs are only 4-6 year old refurbished tech for high prices. I love Macs, but unless Apple suddenly does something drastic with gamers in mind, then no reasons to buy a computer from them just to boot them into Boot Camp. Makes no sense to do that when you can get a cheaper, nicer PC and cut out the middle man (OS X). Not to mention, while Metal got some parts added into it with macOS Sierra, the gaming world is slow/hesitant to even bother with it. Apple doesn't exactly have a remotely decent track record for supporting things like OpenGL, updated drivers and I'd bet a lot they'll let Metal fall to the wayside as is their usual deal.
To the OP, somebody mentioned Razer. I'd steer clear of Alienware and go Razer/Asus/MSI and if you're rich, what Zaphon posted.
With the Razer Blade, you can get a Razor Core to go with it for more power if you want it, though the RazerBlade has a Nvidia 1060 in it now, I think so that alone should cover most gaming needs I'd think. And they've improved them just recently. WTB Sugah Momma or Daddy, I'm not picky for new computer!