  We present a detailed spectral analysis of the recent 1.5\,Ms XMM-Newton
observing campaign on the narrow line Seyfert 1 galaxy IRAS~13224$-$3809, taken
simultaneously with 500\,ks of NuSTAR data. The X-ray lightcurve shows three
flux peaks, registering at about 100 times the minimum flux seen during the
campaign, and rapid variability with a time scale of kiloseconds. The spectra
are well fit with a primary powerlaw continuum, two relativistic-blurred
reflection components from the inner accretion disk with very high iron
abundance, and a simple blackbody-shaped model for the remaining soft excess.
The spectral variability is dominated by the power law continuum from a corona
region within a few gravitational radii from the black hole. Additionally,
blueshifted Ne \textsc{x}, Mg \textsc{xii}, Si \textsc{xiv} and S \textsc{xvi}
absorption lines are identified in the stacked low-flux spectrum, confirming
the presence of a highly ionized outflow with velocity up to $v= 0.267$ and
$0.225$\,c. We fit the absorption features with \texttt{xstar} models and find
a relatively constant velocity outflow through the whole observation. Finally,
we replace the \texttt{bbody} and supersolar abundance reflection models by
fitting the soft excess successfully with the extended reflection model
\texttt{relxillD}, which allows for higher densities than the standard
\texttt{relxill} model. This returns a disk electron density $n_{\rm
e}>10^{18.7}$\,cm$^{-3}$ and lowers the iron abundance from $Z_{\rm
Fe}=24^{+3}_{-4}Z_\odot$ with $n_{\rm e}\equiv10^{15}$\,cm$^{-3}$ to $Z_{\rm
Fe}=6.6^{+0.8}_{-2.1}Z_\odot$.
