Throughout his career, Havoc proved to be an effective leader who truly cared for the men under his command, even as he began to doubt his own future—and those of his clone brethren—in the Republic. The Battle of Concordia saw him meet the Death Watch Trooper Mand Dia, whom he came to respect despite their striking differences. In 21 BBY, his leadership was put to the ultimate test at the Battle of Phatrong, when he was forced to unite the 536th Legion against the Separatist leader Emchic Dong, an extremely violent human who hated clones. Havoc was captured and infected by a brain worm that Dong had kept as a pet. The worm was different from others and Havoc knew what he was doing but couldn't control it. Eventually, Clanker got the worm out, but Havoc was scarred forever.