This presentation explores a notable incident where a SaaS network caused a 500% traffic increase on our IXP port. We will examine the origins and reasons for this event, and dissect the evolution of our AS-SET, pinpointing the exact errors involved. The focus will be on how we identified the mistakes, the lessons learned, and the proactive measures to prevent such incidents in the future. By sharing our experience, we aim to enhance understanding and promote resilience in network management.