Gas inflows from the circumgalactic medium play a key role in governing galaxy evolution by fuelling star formation and black hole growth. Simultaneously, gas outflows are driven to the CGM by supernovae and AGN activity. Thus, the CGM offers a unique perspective for exploring the cosmic systems that shape galaxy evolution. Based on deep integral field spectroscopy with MUSE, I will present results from studying two giant nebulae at z~0.6. The first nebula surrounds quasar HE0238-1904, which resides in an unusually overdense environment for a radio-quiet system. The environment likely consists of two groups which may be merging. The nebula exhibits largely quiescent kinematics and irregular morphology. The nebula primarily arises from interaction-related stripping of CGM/ISM of group members. The upper limits on the electron number density implied by the [O II] doublet ratio are consistent with CGM or ISM origin. However, the densities implied from the measured line ratios between different ions (e.g., [O II], [O III], and [Ne V]) and photoionization simulations are often 10?400 times larger. This large discrepancy can be explained by long-term (10^4-10^5 years) quasar variability which can produce non-equilibrium effects in the CGM. The second nebula surrounds quasar 3C57, a radio-loud quasar residing in a local system hosting 7 group galaxies. The nebula exhibits multi-component emission features, consistent with expectations from a biconical outflow. These systems offer an exceptional opportunity to explore the influence of AGN outflows and group interactions on these galactic environments.