In some aspects, a gas turbine combustor assembly is arranged around a longitudinal axis. The gas turbine combustor comprises a first fuel/air mixer assembly, the mixer assembly comprising a first fuel injector and a plurality of first mixer elements, each mixer element defining an air flow passage therethrough having an outlet in a first plane. A second fuel/air mixer assembly comprises a second fuel injector and a plurality of second mixer elements, and each second mixer element defines an air flow passage therethrough having an outlet in a second plane, longitudinally offset from the first plane.