The laser driver system we describe is coupled to the SOMBRERO reactor concept. This is the Inertial Fusion for Energy (IFE) design concept generated by the W.J. Schafer Team for a recent DOE study1. The nominal plant design has 1 GW electrical output and requires a KrF laser driver system that supplies 3.4 MJ per pulse onto a spherically symmetric, direct drive target, at a repetition rate of 6.7 pps. We describe an architecture which results from the constraints of what must be supplied at the target, coupled with a final amplifier design which makes use of e-beam pumped, angularly multiplexed, 60 kJ final amplifier cavities, recent technology advancements in e-beams and pulsed power, and which has been optimized for system efficiency. Driver system efficiency of more than 7% (“wall plug”), and an effective efficiency of more than 9%, obtained through utilization of laser waste heat, are projected.