Threat Assessment, Prevention, and Safety Act of 2018 This bill directs the Department of Homeland Security (DHS) to establish within itself a Joint Threat Assessment and Management Task Force, which shall provide recommendations to Congress and DHS on the development and implementation of a national strategy for preventing targeted violence through threat assessment and management. The task force shall make recommendations relating to the most effective use of existing government infrastructure, workforce, and experience, unit support, training, and school violence prevention. The bill defines "threat assessment and management" as the systematic and evidence-based process of: (1) identifying individuals whose behavior indicates a capacity for committing acts of violence; (2) investigating and gathering information to assess whether such individuals pose a real threat; and (3) the subsequent management of such a threat. DHS shall develop and implement the national strategy and provide information and training services related to it. The bill directs DHS to award grants to governmental and educational entities and nongovernmental organizations to establish community based units for implementing the national strategy.