  We present an analysis of a 50ks XMM observation of the merging galaxy
cluster ClJ0152.7-1357 at z=0.83. In addition to the two main subclusters and
an infalling group detected in an earlier Chandra observation of the system,
XMM detects another group of galaxies possibly associated with the cluster.
This group may be connected to the northern subcluster by a filament of cool
(1.4^{+0.3}_{-0.1}keV) X-ray emitting gas, and lies outside the estimated
virial radius of the northern subcluster. The X-ray morphology agrees well with
the projected galaxy distribution in new K-band imaging data presented herein.
We use detailed spectral and imaging analysis of the X-ray data to probe the
dynamics of the system and find evidence that another subcluster or group has
recently passed through the northern subcluster. ClJ0152.7-1357 is an extremely
dynamically active system with mergers at different stages occurring along two
perpendicular merger axes.
