Ironman Captain All this started from the storyline of Civil War 2. When movie Civil War released in MCU at that time in comic storyline Civil War 2 was completed. Here we will see great combat between Captian Marvel and IRONMAN. Actually Captain America was responsible for all this and after this, he turned into a villain in the second empire.
Here a conflict Ironman aroused between Captain Marvel and IRONMAN so all the superheroes got divided some joined IRONMAN whereas rest joined Captain Marvel. In the meantime, a superhuman was introduced who was gifted with the power to see the future.
So he announced that Ironman in future Ironman Spiderman will Captain America and he made an illusion with his powers and showed every superhero present there that how Spiderman will kill Captain America. He showed them that at last Spiderman was standing alone holding dead Captain America in his hands.
Actually he was not showing them future in actual he was showing them the possibilities of future that what can happen like doctor Strange did in Infinity War.
Seeing all this Captain Marvel arrests Spiderman and all the superheroes arrive there to free Spiderman including IRONMAN and Captain America. Spiderman says that he will choose to die rather than killing Ironman America. Captain America also says that Spiderman can’t do this, but Marvel refuses to listen to anyone. So a conflict arouses between Captain Marvel and IRONMAN. Ironman tells her that she has no authority to ruin a child’s life on the basis of a stupid Ironman possibility about which there is no proof. But Captain Marvel says that you are just an insect from the earth and I’m a galactic superhero. So they start to fight at the very same place resulting in Ironman’s death.
So this is how Marvel killed Ironman. But let me tell you that IRONMAN secretly performed an experiment on himself due to which he would not die but he went into a coma but his brain was still Ironman conscious and working through a previously designed Artificial Intelligence.