DDOS = Distributed Denial of Service.

"On the Internet, a distributed denial-of-service (DDoS) attack is one in which a multitude of compromised systems attack a single target, thereby causing denial of service for users of the targeted system. The flood of incoming messages to the target system essentially forces it to shut down, thereby denying service to the system to legitimate users.
A hacker (or, if you prefer, cracker) begins a DDoS attack by exploiting a vulnerability in one computer system and making it the DDoS "master." It is from the master system that the intruder identifies and communicates with other systems that can be compromised. The intruder loads cracking tools available on the Internet on multiple -- sometimes thousands of -- compromised systems. With a single command, the intruder instructs the controlled machines to launch one of many flood attacks against a specified target. The inundation of packets to the target causes a denial of service."
---Taken from some website.

Basically, Mantralord is flooding Zelaron with connections.