  Many new and unidentified Galactic sources have recently been revealed by
ongoing hard X-ray surveys. A significant fraction of these have been shown to
be the type of accreting white dwarfs known as cataclysmic variables (CVs).
Follow-up observations are often required to categorize and classify these
sources, and may also identify potentially unique or interesting cases. One
such case is IGR J18007-4146, which is likely a CV based on follow-up Chandra
observations and constraints from optical/IR catalogs. Utilizing simultaneous
XMM-Newton and NuSTAR observations, as well as the available optical/IR data,
we confirm the nature of IGR J18007-4146 as an intermediate polar type CV.
Timing analysis of the XMM data reveals a periodic signal at 424.4 +/- 0.7 s
that we interpret as the spin period of the white dwarf. Modeling the 0.3-78
keV spectrum, we use a thermal bremsstrahlung continuum but require intrinsic
absorption as well as a soft component and strong Fe lines between 6 and 7 keV.
We model the soft component using a single-temperature blackbody with kT = 73
+8/-6 eV. From the X-ray spectrum, we are able to measure the mass of the white
dwarf to be 1.06 +0.19/-0.10 Msun, which means IGR J18007-4146 is more massive
than the average for magnetic CVs.
