Countdown
In the Countdown to Final Crisis tie-in series Lord Havok and the Extremists, a variant version resides on Earth-8. Originally a soldier who was badly injured trying to desert his post, Vincent Cade's broken body was experimented on by the government. Cade was given enhanced strength, speed and senses. He was also forced to endure hours of violent images and subliminal audio telling him to kill. He was implanted with a chip to be controlled with, Tracer's first mission ended with him trying to kill one of his own teammates. Just as his masters were about to use the chip to shut him down, Lord Havok arrived, removed the chip, and offered Tracer a place in his organisation. At Havok's command, Tracer works as an assassin-for-hire for government officials, gaining valuable information on them for his master. In #3, he was attacked and badly beaten by Monarch's forces. Team member Bizarra was eventually able to get Tracer stung up by the neck with her lasso. Only Tracer's enhanced healing ability kept him from dying.
Read more about this topic: Tracer (DC Comics)