In a continuous and swift change of needs in the energy sector, due to multifaceted issues of anthropocene, energy transition has to rely on a suitable energy mix because no unicorn solution is actually capable to give a definitive solution to the problem posed by climate change urgencies. In this paper, the central role of a combustion-based energy system is discussed in relation to its complementarity with Renewable Energy Sources (RES) and their difficulties in ensuring a complete solution to the energy problem. Among others, the availability of critical metals and infrastructures are particularly relevant and may actually endanger the deployment of renewable energy sources. In this panorama, where the exploitation of renewables must be maximized and the effectiveness of energy carriers as storage solution has been proved, combustion plays a primary role. Combustion can be hardly replaced in those sectors where very high temperatures are involved, and in general in the whole hard-to-abate sector that is among the major contributors to CO2 emission in the atmosphere. From this perspective, combustion systems are a key ingredient in the energy transition but they have to meet three criteria: they have to be efficient, fuel flexible and clean. MILD combustion has been proven to satisfy all these criteria. This paper aims to highlight the emergent features of MILD combustion through simple and immediate examples, looking at its characteristic reactive structure at microscale, its stability as well as its fuel and operational flexibility that enable this combustion process to be an effective support to the energy transition process.