Observations of the inner accretion flows in Active Galactic Nuclei are vital for our understanding of how black holes grow and effect their environments. In this talk, I will present the newest observational tool for probing the inner accretion flow, called X-ray reverberation mapping. Similar to Optical reverberation, where light travel time delays of days or weeks map out centi-parsec scales in the Broad Line Region, X-ray reverberation reveals time delays of tens of seconds, which map out microparsec scales close to the black hole event horizon. I will give an overview of the recent discoveries in X-ray reverberation mapping, and discuss how this technique is being used to put new constraints on the X-ray emitting region and the accretion disc geometry. Lastly, I will present the recent discovery of reverberation in a tidal disruption event, which shows the formation of a super-Eddington accretion flow around a usually quiescent black hole.