Okay I just did that.
Here's what is says:
/usr/bin/cd: line 4: cd: "/Applications/Diablo: No such file or directory
Which is weird coz' I did install it in my Applications folder. I'm looking right at it. :|
Make sure you do not remove the quotes or it will fail because of the space between Diablo and III. If it's on the default location just copy and paste that command.
You could also get there by typing
cd /Applicationsand then
cd "Diablo III"