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After a quiescence period of about 10 years, the classical EXor source V1118Ori has undergone an accretion outburst in 2015 September. The maximumbrightness (DV > 4 mag) was reached in 2015 December and was maintained forseveral months. Since 2016 September, the source is in a declining phase.Photometry and low/ high-resolution spectroscopy were obtained with MODS andLUCI2 at the {\it Large Binocular Telescope}, with the facilities at the Asiago1.22 and 1.82 m telescopes, and with GIANO at the {\it Telescopio NazionaleGalileo}. The spectra are dominated by emission lines of \hi\ and neutralmetallic species. From line and continuum analysis we derive the mass accretionrate and its evolution during the outburst. Considering that extinction mayvary between 1.5 and 2.9 mag, we obtain m_acc= 0.3$-$2.0 10$^{-8}$ m_sun/yr, inquiescence and m_acc= 0.2$-$1.9 10$^{-6}$ m_sun/yr, at the outburst peak. TheBalmer decrement shape has been interpreted by means of line excitation models,finding that from quiescence to outburst peak, the electron density hasincreased from $\sim$ 2 10$^9$ cm$^{-3}$ to $\sim$ 4 10$^{11}$ cm$^{-3}$. Theprofiles 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 kms$^{-1}$. The metallic lines likely originate at the base of the accretioncolumns, where neutrals are efficiently shielded against the ionizing photons,while faster ionized gas is closer to the star. Outflowing activity istestified by the detection of a variable P Cyg-like profile of the H$\alpha$and \hei\, 1.08\,$\mu$m lines.

The 2015-2016 outburst of the classical EXor V1118 Ori