The Underdog Fantasy promo code ON3 is your ticket to claiming one of the DFS industry’s best welcome offers. New users who sign up and use this code can receive a 50% match worth up to $1,000 in bonus cash on their first deposit. If you’re looking for the details behind this welcome offer or the Underdog Fantasy platform in general, this review is for you. I’ll dive into everything you need to know about the Underdog promo code plus the DFS product’s mobile app, website, and various contest formats. What Is the Underdog Fantasy Promo Code?The Underdog promo code is ON3. When you use this code…