Gaming laptop

Currently I have a decent gaming desktop. Diablo 3 max settings 4k monitor works great. Overwatch and sc2 also no video lag. Unfortunately I am losing my office and it is being moved to a more inconvenient space where if I go game I am far from my family.

I am looking at Alienware and other laptops to replace my desktop. Something I can run d3 on when not at my desk, and when I get to my desk run my 4k monitor. The graphics amplifier is an interesting idea. Trying to stay in 15 inch laptop for 1500 bucks. Any suggestion?