Warning! Spoilers for Free Comic Book Day X-Men #1 as well as the teaser for Marvel's Dark Ages arc
Tony Stark has suffered some seriously painful injuries during his time as Iron Man and has continually come back stronger than ever. But, in a preview for the upcoming Dark Ages arc, Iron Man experiences one of his most gruesome injuries to date, as he loses his foot after colliding with a plane and crashes hard into Stark Towers.
Tony Stark has a penchant for deadly experiences in the pages of Marvel Comics. He's been nearly killed by his own sentient armor, was decapitated in the Infinity Gauntlet storyline, was killed by Captain Marvel during Civil War II, and had been living as an A.I. His recent history has been complicated as Marvel will be doing a soft reboot on Iron Man, allowing the character to returns to his roots (and not be intertwined with the messy A.I. arc). But in a tease for a new arc for Tony, he suffers another devastating injury.
In Marvel's Free Comic Book Day X-Men #1, there's a small tease for the upcoming Dark Ages series from Tom Taylor, Iban Coello, Brian Reber, and Joe Sabino. The story opens up with some sort of Earthquake, as Tony advises Pepper Potts to get into the bunker as he investigates what the issue is. Soon after, the power cuts out everywhere: Pepper gets stuck in an elevator, Tony's distress call to the Avengers doesn't go through, and Stark's Iron Man suit immediately begins to shut down mid-air. As Stark flails in the sky as his suit completely powers down, he gets struck by a falling plane. The plane slices through Stark, cutting off his foot. As the plane crashes to the ground, Stark is sent crashing through Stark Towers.
As Tony lays bleeding on the ground, he tells Pepper Potts that everything has "all gone... dark... forever."
Getting hit by a crashing plane and losing his foot is without a doubt one of the most gruesome injuries Iron Man has ever suffered. With the power being completely shut off, Stark can only watch as he freefalls through the air. Getting struck by the plane is bad luck in a very bad situation. Whether Tony survives is unclear (all power being shut off isn't great news for his arc reactor), but the upcoming Dark Ages arc is going to be quite dramatic - at least that's what the tone of these preview pages suggest.
Iron Man has survived some terrible situations and battles, but even if he makes it out of this incident alive, he's going to have major struggles continuing on as a hero. Without his suit and missing one of his feet, navigating through Marvel's Dark Ages (and it's seemingly separate continuity) is going to be extremely tough. If anyone can find a way to adapt and survive, it's Tony - but even Iron Man has his limits to how much he can take.