HOW TO PLAY MTG ARENA ON MAC MOJAVE OS INSTALL
If you complete installation of MTGA and are getting DirectX 11 errors, come back to this step and give these toggles a try. Note: If you have a newer Mac, you may need to click "Screen Options" and then uncheck "Auto Detect GPU Info for Direct3D" and check "Use Mac Driver instead of X11".
IMPORTANT UPDATE: This will no longer work if you upgrade to macOS Catalina, as Wine and Wineskin are 32-bit.
HOW TO PLAY MTG ARENA ON MAC MOJAVE OS HOW TO
I modified uhohohdear's instructions and then added support for Retina/HiDPI displays and instructions about how to update MTGA. The following instructions are heavily inspired by /u/uhohohdear. Installing MTGA on macOS using Wine, and making it look pretty!