  After a quiescence period of about 10 years, the classical EXor source V1118
Ori has undergone an accretion outburst in 2015 September. The maximum
brightness (DV > 4 mag) was reached in 2015 December and was maintained for
several months. Since 2016 September, the source is in a declining phase.
Photometry and low/ high-resolution spectroscopy were obtained with MODS and
LUCI2 at the {\it Large Binocular Telescope}, with the facilities at the Asiago
1.22 and 1.82 m telescopes, and with GIANO at the {\it Telescopio Nazionale
Galileo}. The spectra are dominated by emission lines of \hi\ and neutral
metallic species. From line and continuum analysis we derive the mass accretion
rate and its evolution during the outburst. Considering that extinction may
vary between 1.5 and 2.9 mag, we obtain m_acc= 0.3$-$2.0 10$^{-8}$ m_sun/yr, in
quiescence and m_acc= 0.2$-$1.9 10$^{-6}$ m_sun/yr, at the outburst peak. The
Balmer decrement shape has been interpreted by means of line excitation models,
finding that from quiescence to outburst peak, the electron density has
increased from $\sim$ 2 10$^9$ cm$^{-3}$ to $\sim$ 4 10$^{11}$ cm$^{-3}$. The
profiles of the metallic lines are symmetric and narrower than 100 km s$^{-1}$,
while \hi\, and \hei\,\,lines show prominent wings extending up to $\pm$ 500 km
s$^{-1}$. The metallic lines likely originate at the base of the accretion
columns, where neutrals are efficiently shielded against the ionizing photons,
while faster ionized gas is closer to the star. Outflowing activity is
testified by the detection of a variable P Cyg-like profile of the H$\alpha$
and \hei\, 1.08\,$\mu$m lines.
