You have to finish the regular story mode.
To face Devil Doom on Shadow the Hedgehog you need to unlock the Last Way stage. To unlock The Last Way you need to have gone through all the possible paths in the story and seen all the other endings. Devil Doom is the boss you face after completing The Last Way.
You must clear all 10 finals.You will unlock the final story when you clear the stage you will face Devil Doom.In that battle you are Super Shadow.
ummm...excuse me?
Dr. Doom
who knows if somebody sees your face there will be one!!!
When the sun is shining in your face, your shadow will be behind you.
in back of you
James A. Garfield
shadow
5
The Devil.
Ravenswood - 2013 The Devil Has a Face 1-4 was released on: USA: 12 November 2013