Across the armed forces, warfighters are required to perform in complex, dynamic, networked environments. Adequate preparation requires training in robust simulations that replicate these situations. Designing a training environment for Air Support Operation Center (ASOC) personnel comes with a unique set of challenges. The ASOC warfighters are required to work within their team of nine as well as, with an undefined number of personnel external to their location. The problem in creating a simulated training environment for local training at the operational unit is that it has been proven to be difficult to access, on a regular basis, thirty role-playing warfighters across different locations in order to staff an exercise. The purpose of this paper is to introduce an ongoing effort to create a robust ASOC training environment – the Joint Theater Air Ground Simulation System (JTAGSS) – which overcomes this limitation. JTAGSS incorporates the nine personnel who work within the ASOC, as well as, reflex agents playing the role of team members external to the ASOC (e.g., Joint Terminal Attack Controllers, F16, Joint Fires, etc.). Reflex agents are software-generated role players which are smart, synthetic, team members. Using Mission Essential CompetenciesSM (MEC) the research team identified the primary competencies, supporting competencies, knowledge, skills, and developmental experiences that an ASOC warfighter requires for successful mission completion. The MECs were then leveraged to design and create JTAGSS to provide a training platform to address current ASOC training gaps. This paper presents the successes and lessons learned through creating this unique training environment.