In this talk, we will introduce our ongoing efforts to understand the propagation of Lyman continuum and Lyman alpha photons from giant molecular clouds (GMCs). For this purpose, we perform a suite of radiation-magneto-hydrodynamic simulations, called PRALINES, using a sink particle algorithm and stellar feedback. We show that high surface density, high metallicity, and weak turbulence tend to lower the escape fraction of LyC photons (f_LyC). The escape is most efficient if the total star formation efficiency in the GMC is ~20%. The propagation of LyA forms a characteristic sequence in the Vsep-f_LyC plane, suggesting that this may still be useful to infer the kinematic information about the ISM/CGM.