Hui Lin was born in 1320 in Nanjing, China. In 1368, Hui Lin killed a Mongolian soldier and gave him the message that the Khan's reign was over, stating that himself was the sword that would pierce Kublai Khan's heart. The Ming Dynasty then overthrew the Yuan Dynasty.
He survived to the modern era because of his advanced longevity.
When Carol Danvers, AKA Ms. Marvel was appointed to lead the Mighty Avengers, she put together her own team separate from them, Operation: Lightning Storm. He accompanied and assisted in her adventures with that team, being the only original team member to survive, besides Carol herself.
- Regenerative Healing Factor: Agent Sum's primary power seems to be an accelerated healing process, similar to Wolverine's, that enables him to regenerate damaged or destroyed tissue with far greater efficiency than an ordinary human. The full extent and speed of his healing factor are not known, though he has been shown to fully heal from falling from massive heights and surviving blows from individuals with super strength. Among the more extreme depictions of his accelerated healing factor involved him having his skin, muscles, and internal organs incinerated leaving only his skeleton and fully regenerating the tissue within moments.
- Superhuman Longevity: While most of his past is unknown, Agent Sum has been alive since the 1300s. Hence, he is several hundred years old. In spite of his age, however, he has the physical appearance and vitality of a man in his prime.
S.H.I.E.L.D. spy, marksmanship, and espionage training
Standard S.H.I.E.L.D. equipment
Many types of S.H.I.E.L.D. issue handguns and rifles
He is a top-ranking S.H.I.E.L.D. agent, so classified, that only about 3 people have security clearance high enough to know the truth about his origins.