  We present the analysis of X-ray and optical observations of gas filaments
observed in the radio source 3CR 318.1, associated with NGC 5920, the Brightest
Cluster Galaxy (BCG) of MKW 3s, a nearby cool core galaxy cluster. This work is
one of the first X-ray and optical analyses of filaments in cool core clusters
carried out using MUSE observations. We aim at identifying the main excitation
processes responsible for the emission arising from these filaments. We
complemented the optical VLT/MUSE observations, tracing the colder gas phase,
with X-ray $\textit{Chandra}$ observations of the hotter highly ionized gas
phase. Using the MUSE observations, we studied the emission line intensity
ratios along the filaments to constrain the physical processes driving the
excitation, and, using the $\textit{Chandra}$ observations, we carried out a
spectral analysis of the gas along these filaments. We found a spatial
association between the X-ray and optical morphology of these filaments, which
are colder and have lower metal abundance than the surrounding intra-cluster
medium (ICM), as already seen in other BCGs. Comparing with previous results
from the literature for other BCGs, we propose that the excitation process that
is most likely responsible for these filaments emission is a combination of
star formation and shocks, with a likely contribution from self-ionizing,
cooling ICM. Additionally, we conclude that the filaments most likely
originated from AGN-driven outflows in the direction of the radio jet.
