SPECS:
Steam system information report
Kernel: 4.14.67-1-lts x86_64
Desktop Env: i3 4.15
Distro: Antergos Linux (Arch Linux based)
Device: laptop System: CLEVO Mobo: P370EM
CPU: Quad core Intel Core i7-3740QM (-MT-MCP-) 3700 MHz
Graphics:
GPU: NVIDIA GK104M [GeForce GTX 670MX]
Display Server: X.Org 1.20.1 Resolution: 1920x1080 60.02hz
OpenGL: renderer: GeForce GTX 670MX/PCIe/SSE2
Nvidia driver version: 4.6.0 NVIDIA 396.54
Memory: 16 GB

The game fails to start. I noticed these two lines in the Proton log:

124076.437:0025:0026:err:vulkan:wine_vk_init Failed to load libvulkan.so.1.
124076.437:0025:0026:err:vulkan:wine_vk_init Failed to load Wine graphics driver supporting Vulkan.

Dota2 (native, not Wine) using Vulkan work just fine though, so I think my GPU should be able to use DXVK.
Using PROTON_USE_WINED3D11 works but the performance is terrible and some graphical glitches, obviously the OpenGL renderer is not ideal here.

Using Proton 3.7.5 beta.