Large scale mass casualty incident (MCI) simulations present unique design, logistical, and educational challenges for simulation teams. This session presents a reflective, practical overview of an Interprofessional Mass Casualty Incident Simulation, framed as a how to guide for simulation professionals. We will explore key elements of preparation, including scenario design, stakeholder coordination, resource management, and faculty readiness. The execution of the event will be examined through an operational lens, highlighting real time adaptations, communication strategies, and emergent challenges. Finally, we will reflect on lessons learned, unanticipated outcomes, and practical recommendations to inform future large scale MCI simulation planning and delivery.