Ran through the cast to make a quick list of who Dormammu can get easy double relaunches off of in the corner. Way to do the relaunch is as simple as dashing up to them and laying down a flame carpet. If you want to do 2 launches off one carpet, launch them after the 3rd bounce, then you can re-launch them when they land on the carpet again. Or you can launch them after the 5th bounce, and lay down another carpet to relaunch.
This is just a short simple list for people who might be wondering who it works on.
For all other characters, if you do a flame carpet in the corner they will hit it once, then go into knockdown, and if they don’t roll out they will be forced to block the rest of the carpet. A nice thing you can do with this is jump up and do a quick dashdown L which will catch them if they don’t switch from low to high block in time.
Characters:
Firebrand
Arthur - Arthur is a bit special in that he bounces a lot faster, it is possible to do 2 launches off a single carpet but it is much easier to just let him bounce 5 times then do a new carpet.
Rocket Raccoon
Wolverine
Tron
Viewtiful Joe
Amaterasu
The flame carpet relaunch works on all characters in the corner except She-Hulk, Iron Man and Doctor Strange. The timing differs based on hurtbox and bounce after air finisher.
The list are for the easy and practical relaunches. (Ones that require no timing or spacing) Since getting a relaunch with flame on other characters in an actual match isn’t exactly that consistent.
They are all practical. Spacing and timing is also required for the characters you listed, it is just easier for small hurtboxes. 
Cosmic’s right but I feel as though what we should instead do is write how to get the relaunch on all the characters. Much easier to have all the info on how to do it be available than just saying “it can be done” and letting everyone test every single character to figure out how. And note, I mean that in no offense to your comment, just that I know something like that would really help EVERY Dorm player.
Only person I can get it semi-consistently on that’s not listed is Vergil. From what I could tell, it was a matter of how fast you did everything from the air combo to flame carpet. Gonna have to re-test tho since I havent messed with it in awhile.
The spacing required for my listed characters are literally just hugging the wall. That’s what makes them so practical. You don’t need to judge anything. You just walk up to the corner and put down a carpet. No special timing required.
Lol just noticed this thread now I made a video about this on who can be relaunched.
