"The first Avenger falls" was the teaser for the fourth chapter of "Avengers: No Surrender", Avengers #678. The issue revealed that the event's first major casualty was the Human Torch. As it happened on the final page, his death wasn't made perfectly clear in the comic, but series writer Jim Zub confirmed it in a recent interview.
This isn't the Human Torch's first brush with death. In a 2011 storyline titled "Three", Johnny Storm was killed fighting aliens from the Negative Zone. As a result, Spider-Man took Torch's place in the Fantastic Four and the team was renamed Future Foundation. Toward the end of the same year, Torch was revived by Annihilus who sought to use Torch as a pawn. In 2015, Torch joined the Avengers Unity Squad, a team initially made up of Avengers and X-Men. The character has remained a key member of the group ever since.
In Avengers #678, two teams of Avengers battled with the Lethal Legion and the Black Order, while still trying to understand who was responsible for kidnapping the Earth and trapping all of its heroes in stasis. What the Avengers don't know is that they're all just obstacles in a cosmic game between the Grandmaster and a new villain called the Challenger. The Avengers eventually realize that the prize both teams are fighting over is a mysterious object called a pyramoid. Red Hulk (Robert Maverick) was about to grab it when the Human Torch swooped in and snagged it, causing a burst of energy to surge through his body.
The hero's fate was left up in the air until writer Jim Zub explained the issue's cliffhanger in an interview with Newsarama. Zub confirmed that Torch was "vaporized" when he "sacrificed himself" by touching the pyramoid. Zub says that Torch didn't know that he would die, but being a hero "through and through," knowing the truth wouldn't have stopped him. Zub also commented on what the loss of the Human Torch means for the remaining issues of the 16-part series:
The Avengers are on the ropes and their numbers are going to get thinned out. This issue notches one, but it won’t be the last. With a cast of over twenty heroes you knew we had to start knocking some of them off...
The moment came as a surprise to fans, despite the fact that the writers of the series have teased several deaths. The events of the previous issue put Quicksilver in the gravest amount of danger. Furthermore, many likely assumed that Human Torch would be safe considering that he's currently a main character in Marvel Two-In-One. Zub says this fact is one of the reasons why they thought having Torch take the fall would "pull the rug out from everyone."
Since Marvel characters rarely stay dead, plus the fact that Marvel seems to be planning on reuniting the Fantastic Four, fans have plenty of reasons to suspect that Human Torch will be back before too long. Otherwise, Mr. Fantastic and Invisible Woman's return to the Marvel Universe won't make for much of a happy reunion.
The fourth chapter of "Avengers: No Surrender", Avengers #678 is on sale now.