Towards the end of the Battle of Hue in Vietnam, the Taskforce found themselves in a planning meeting to figure out the best course of action. During the meeting, an explosive tore through the building they were stationed in, they immediately began to attempt their escape. Right at the exit, most of the wall collapsed, preventing anyone from leaving while the building was crumbling around them. Dr Hardy Weber, the hero known as Serum, injected himself with the most experimental serum in his arsenal, one that he saved for a moment exactly like this. It drastically increased his strength, allowing for him to support the entire weight of the collapsing building on his back, saving every life... except his own. The duration of the serum lasted barely long enough, but it immediately reversed the effects of all the serums to pause his muscular dystrophy, immediately atrophying his muscles to how they would have been at his age. If the weight of the building didn't kill him, the respiratory failure and immediate pulmonary collapse would have.
This is believed to be the first death of a Powered hero in history, his death immediately causing the disbanding of the team he helped create. But he inspired countless others to follow in his footsteps, for both good and ill. After the Taskforce moved to Brownbridge, New Mexico they donated his body to science as he asked, and put his suit up as a memorial in their headquarters.