X-ray astronomy has entered a new era with the launch of XRISM, enabling high resolution
spectroscopy of extended sources. We are now able to probe the velocity structure of the
hot intracluster medium (ICM) of galaxy clusters, revealing the influence of gas motions
on the dynamical state of these systems. I will first present recent results from XRISM
observations of Abell 2029, a rich, relaxed cluster of galaxies that is an ideal target
for measuring the contribution of gas motions to the overall pressure support of the
ICM. We find low velocity dispersion well beyond the central region of the cluster,
indicating that deviations from hydrostatic equilibrium are small and that the cluster
is indeed extremely relaxed. In the second half of the talk, I will introduce AXIS, an
X-ray Probe mission concept that is currently in competition for selection by NASA,
boasting high spatial resolution and high throughput. I will review the exciting science
goals of AXIS, and detail the design of the high-speed X-ray camera currently under
development by our group.