Doom was seemingly killed when he fell into the collapsing surface, forcing Richards, Grimm, and Johnny to leave him and return to Earth, but not before an accident occurs that gives the three survivors and Susan Storm unique superhuman abilities.
Doom was seemingly killed when he fell into the collapsing surface, not before having some of the erupting green substance to fall on him, and seemingly mutate him. This forces Reed, Ben, and Johnny to leave him and return to Earth, but not before an accident occurs that gives the three survivors and Susan Storm unique superhuman abilities.