XMM has been operating for 15 years and is likely to operate for another 10. Much of its scientific legacy will come not from targeted studies of individual objects, but from serendipitous detections and from contiguous area surveys. This session will showcase recent serendipitous and survey science from XMM and look forward to how science in these areas will benefit from the launch of eROSITA and Athena. The focus will be extra galactic, especially cluster and AGN studies, although presentations on Galactic X-ray sources will also be welcome.