How can I run Warcraft 3 on my new MacBook Pro
From https://us.battle.net/support/en/article/playing-older-blizzard-titles-on-mac-os-x-10-7-lion : 


  Warcraft III will only run on Mac OS X 10.7 if your operating system
  was upgraded from 10.6.X and only if the Warcraft III installation was
  patched before the operating system was upgraded. There is currently
  no way to install or patch the game on Lion.


So you need a 10.6 system to bootstrap from.