Reverberation Mapping (RM) provides the only tool to determine Black Holes (BH) masses directly, but so far this method has been applied only to small and intermediate luminosity systems (L<10^46 ergs/s). We are extending these studies by two orders of magnitude, probing the BH-mass of luminous AGN at redshift 2-3, obtaining the measurement of the largest BHs and extending our knowledge of the physics of AGN and their hosts into the most crucial epoch in galaxy evolution. Since 2005 we have been monitoring very luminous Quasars using broad-band imaging with the SMARTS telescopes and in 2007 we started the RM campaign of our most variable targets obtaining spectroscopic follow-up with the du Pont telescope. After 10 years of data gathering we are finally able to report on the RM for Quasar J221516 as well as several other systems that should yield results in the near future.