  We present a detailed study of the 2016 eruption of nova V407 Lupi
(ASASSN-16kt), including optical, near-infrared, X-ray, and ultraviolet data
from SALT, SMARTS, SOAR, Chandra, Swift, and XMM-Newton. Timing analysis of the
multiwavelength light-curves shows that, from 168 days post-eruption and for
the duration of the X-ray supersoft source phase, two periods at 565 s and 3.57
h are detected. We suggest that these are the rotational period of the white
dwarf and the orbital period of the binary, respectively, and that the system
is likely to be an intermediate polar. The optical light-curve decline was very
fast ($t_2 \leq$ 2.9 d), suggesting that the white dwarf is likely massive
($\gtrsim 1.25$ M$_{\odot}$). The optical spectra obtained during the X-ray
supersoft source phase exhibit narrow, complex, and moving emission lines of He
II, also characteristics of magnetic cataclysmic variables. The optical and
X-ray data show evidence for accretion resumption while the X-ray supersoft
source is still on, possibly extending its duration.
