Intracluster medium (ICM) constitutes 90% of the baryons in galaxy clusters. The centers of the ICM often feature a sharp X-ray surface brightness peak. AGN mechanical feedback from the BCG is likely preventing the hot ICM from the catastrophic cooling, although the exact feedback process remains poorly understood. A growing number of kiloparsec-scale multiphase filaments have been observed at cluster centers, mainly in H_alpha and CO, which would provide new insights into the feeding and feedback process in these systems. We have applied a blind source separation algorithm to the Chandra observations of a number of cooling flow clusters, which allows X-ray filaments to be isolated from the underlying cluster atmosphere. We found that the surface brightness of X-ray filaments appear to correlate with that of H_alpha, revealing the intimate relation of multiphase gas. ICM is also the reservoir of nearly all the metals that have ever been produced by member galaxies. In this talk, I will also present our recent study on the metal content of the ICM from cluster centers to the virial radii, as well as its implication for the enrichment process of the ICM. I will also discuss our recent work on AGN populations in galaxy clusters.