The Shadow Blot is the version of the Phantom Blot who appears in Epic Mickey. A destructive giant monster made of paint and thinner accidentally created by Mickey Mouse, the Shadow Blot long rampages Wasteland, seeking a way to escape it and continue his terror in Mickey's world.
When visiting Yen Sid's workshop and playing with magic paint, Mickey Mouse accidentally creates a monster and quickly tried to erase it using thinner. However, what Mickey erases goes back into the jug and falls into Wasteland, causing the Thinner Disaster and setting the Blot Wars into motion. Allying with The Mad Doctor, the Shadow Blot comes very close to victory, only to be sealed away in the Jug by Oswald the Lucky Rabbit and Ortensia, though at the cost of Ortensia's life.
Ever since that time, the Blot's presence remains in Wasteland through the various drippings that escaped the Jug, the largest of which become the Blot's eyes and ears in Wasteland.
Continuing his work with the Blot and commanding the Blotlings in his stead, the Mad Doctor works on a plan to allow the Shadow Blot to reach through the portal to Wasteland into Mickey's world and capture another toon to steal their heart. Chosing the character with the biggest heart of them all, Mickey, the Blot drags the mouse down into Wasteland, though the Mouse manages to bring Yen Sid's magic paintbrush with him, frightening the creature off upon seeing it.
While Mickey travels through Wasteland to find rocket parts to get back home, the Shadow Blot built his army up to assault Oswald's Fortress on Mickeyjunk Mountain and open the Jug. Mickey foiled the fake Blot on the mountain summit, but when Mickey confessed that he was the one responsible for causing the Thinner Disaster and creating the Blot, an enraged Oswald accidentally broke the Jug open, releasing the real Blot.
Ransoming the lives of Oswald and Gremlin Gus for Mickey's heart, the Blot then proceeded to begin absorbing all of Wasteland's paint with Bloticles attached to the ground. Mickey destroyed these connections and he and Oswald planned to attack him with the Moonliner rocket. Absorbing the paint from the rocket and causing it to crash land in Dark Beauty Castle, Oswald came up with another plan to defeat the Blot--bombard him with fireworks, setting the stage for Mickey's final battle where he must activate the fireworks and eventually gets dragged inside the Blot to get his heart back by force.
After breaking his heart free, Mickey's heart is given back to him by Oswald and the Lucky Rabbit hits the button to launch the fireworks, destroying the Blot in a series of colorful explosions that also serve to send Mickey back home, as well as causing a rain of paint to fall over Wasteland, changing it back into the paradise that it once was.
The Shadow Blot is mentioned a few times by the residents of Wasteland and Oswald throughout the game. Since its destruction, the Blotlings ran rampant in Mean Street until they were moved into Blot Alley in Bog Easy. The Blotlings seem to hate Mickey as he is the one that destroyed the Blot, leaving them homeless.
The Blot makes a non-physical appearance as part of a diorama in the old train tunnels while Mickey and Oswald chase after Prescott. The diorama retells Mickey's victory against the Blot using the fireworks atop Dark Beauty Castle.
The Shadow Blot was present in the earliest concepts for Epic Mickey as the force that brought Mickey into Wasteland. As a revamped version of the Phantom Blot, Warren Spector intended on expanding the threat the Blot posed compared to his camera-stealing motivation in his original appearance. The character's name was changed when the crew deemed that their revamped Blot had become very far removed from the original and in keeping with the "familiar but strange" feeling of the use of some characters.