Opportunities to Provide for Illicit Opioid Interdiction and Detection Act of 2018 or the OPIOID Act of 2018 This bill requires the Department of Homeland Security and the U.S. Customs and Border Protection to jointly develop technology to (1) screen mail, items, and containers entering the United States for narcotic drugs; and (2) screen motor vehicles, pedestrian traffic, and cargo entering the United States at a land border port of entry for narcotic drugs.