inverse fourier transform of magnitude and phase
You can express a complex signal $y$ as $|y|.e^{i \phi_y}$ where $|y|$ is the magnitude and $\phi_y$ is the phase. You can use Inverse the Fourier transform formula:
$$\displaystyle y(t) = \frac{1}{2\pi}\int_{-\infty}^\infty Y(\omega) e^{j\omega t} d\omega$$
You can express $Y(\omega)$ in $|y|.e^{i \phi_y}$ form and then perform the IFFT. But I am not sure if a minus comes in magnitude unless its in dB.