 $d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2 + (z_2 - z_1)^2}$\\  where:\\ \hspace*\leftmargin $(x_1, y_1, z_1)=$ enemy's coordinates\\ \hspace*\leftmargin $(x_2, y_2, z_2)=$ player's coordinates 