Late lean injection with expanded fuel flexibility

A gas turbine engine (10) is provided and includes a fuel circuit (70), including multiple fuel circuit branches (71, 72), a combustor (20) having a first interior (21) in which a first fuel supplied thereto by any one of the multiple fuel circuit branches (71, 72) is combustible, a turbine (50), a transition zone (43), including a second interior (41) in which a second fuel supplied thereto by any one of the multiple fuel circuit branches (71, 72). The second fuel includes gas receivable by the fuel circuit (70) from an external source, and the products of the combustion of the first fuel are combustible, the transition zone (43) being disposed to fluidly couple the combustor (20) and the turbine (50) to one another. A plurality of fuel injectors (60) supply the second fuel to the second interior (41) in any one of a single axial stage, multiple axial stages, a single axial circumferential stage and multiple axial circumferential stages.