The Scrapped Halloween Special is an Eddisode that was considered for production, but was never created due to the content. In an Eddsworld Q&A, Tom was asked "What was that whole really creepy episode that Edd came up with that you mentioned on Vokle a few times?"
He answered "It was a Halloween special about Matt having died years ago and being a figment of Tom’s imagination ever since. The dark twist at the end of the Eddisode was going to be that actually both Matt and Tom are figments of Edd’s imagination. The Eddisode would’ve ended with a realistically drawn version of Edd sitting down and doing impressions of the characters while drawing them into his computer. It was pretty messed up, haha."
The blog can be found here: http://thetomska.tumblr.com/post/82827526898/eddsworld-q-a