Injector assemblies (12) and ducting arrangement (20) including such injector assemblies are provided. The injector assembly may include a reactant-guiding structure (16) arranged to convey a flow of reactants (19) into the combustion stage and means for injecting (24, 25, 26) a flow of air (22) into the combustion stage. The flow of air injected into the combustion stage may be arranged to condition interaction of the flow of reactants injected into the combustion stage with a cross-flow of combustion products (21), as the flow of reactants is admitted into the combustion stage.