This was a really crazy dream. It's a shame I can't remember most of it... It involved Soul Eater, Fullmetal Alchemist, Plasma's Folly, the Kirby anime, and real life stuff.
It was never explained why, but Ed became Envy's host, like how Greed fused with Ling. It showed him, Al, Hawkeye, and Mustang driving across this random desert in what I think was a convertible. All of the sudden, Ed started shouting, and everyone started asking him what was going on. Before he had a chance to respond, he started to morph into Envy's monstrous shape; I guess Envy had taken over his body. Even though Envy (unless he's reduced to his true form) is supposed to have the same mass in all his shapes, Edvy became dramatically heavier when his transformation was initiated. It probably had something to do with how he was using Ed's body as a host. His rapid weight gain caused his side of the car to become crushed, and his new enormous form spilled out into the sand. Everyone else fled from the car before it was totally destroyed, and then that part of the dream ended.
The next part is what was the most unclear; I believe it had something to do with Mack being an evil genius, and how I was trying to decipher his schemes. At one point I randomly started watching Who Wants to Be a Millionaire, which turned into a soap opera involving Escargoon and some other character I can't remember. It might've been Bowser...? Later, I arrived at the set of this freaky game show that featured this huge obstacle course. I had to get through it, and when I did, I was warped to my house. Someone explained that Mack had been possessed by an evil demon, and that I expelled it from his body by completing the course. Jackie was also alive again, and he started meowing when he saw me. There was also this weird tortoiseshell cat that supposedly also came back from the dead. Somewhere along the way, I wanted to become a Pokemon hybrid, but these people in China had obtained the formula and they destroyed it. Also, Sid the zombie and Excalibur were in my front yard, and Sid tied up Excalibur with rope in front of the garage and started stabbing him repeatedly. He was apparently a homunculus, so he simply regenerated and was perfectly fine. I think there was also a part with a bowling alley...? I don't know, I know I'm missing a lot of the dream.