Mantis first appeared in #112, but it was in this issue where she really starts to shine. She was an interesting character. Writer Steve Engleheart won the Eagle Award and was a psychology major; his work tended to be thoughtful. I think of him as a less “out there” version of Steve Gerber. She was the daughter of Libra (part of the Zodiac gang–a bunch of bad guys who repeatedly fought The Avengers), and as far as I know she was the first Vietnamese superhero. Right about this time, Jim Starlin was hanging out at the Marvel offices quite a bit and talking about his experiences during the Vietnam war.
Also, she’s a sex object.
Also in this issue: Swordsman joins. Despite that he’s been a frequent Master of Evil.
He and Mantis are immediately an item. Together they seem to betray The Avengers, but in the end Mantis says it was all a trick. She and Mantis fake-betrayed the team to get closer to the villain-of-the-month (a “Lion God”).
Cap is still suspicious. As he should be. Swordsman has been an established villain, frequent asshole, and all-around stupid character for all of his existence.