its definitely the reverse reverb track into a clean track. BUT theres many ways to get this sound. You'll notice its a a few semitones higher. That could be from blasting feedback on a chorus before going into the reverb. I suggest creating a nasty bass and bouncing it to a new track. then automate EVERYTHING on it with no musical purpose or timing. . . .chorus, reverb, phaser. push it past your comfort zone and what you know it will sound like. if you have a 16 bar bass line and do this to it, you'll then have the original and a super processed one. you'll be able to chop up the processed one and place the incidental bits where you want them. If you ask spor how he made that EXACT little bit, he'lll have an answer, but it might not be the right one because he probably wouldn't remember.
Experimentation is key here. Theres so many ways to make that sound, so the more you experiment, the more tools you'll have to make any sound you hear.
keep pushing sound past your knowledge of what the results will be and you'll have some awesome sounds to work with. . . . .always save the results, you never know what you'll use them for.
The only thing i can say with absolute certainty is, its an effect tail reversed.
