Here's an Associated Press account of Rantissi's death. After his car was hit by the IDF,
Rantisi ran about 15 yards from the car, collapsed and lost consciousness[...]. The Hamas leader, his body pocked with bloody wounds and blood streaming from his head and neck, was rushed to the hospital and into emergency surgery, but he died five minutes after arriving.
As a commenter said at Little Green Footballs,
This means he experienced some moments of fear and terror, and the meaning of justice.