The supernova potion seems to be a great conflag on crack (lol) and can only be used every 2-3 minutes? not sure exactly at least 2 minutes. When you use it; it reminds u of when a gm comes on screen and it looks like a 10x10 area around the user is engulfed in flames for a hit.
The other (not named) seems to be a potion that increases your stamina regeneration for somewhere between 10-20 seconds. Not sure on the reuse timer of it. I only used one.
Hope that helps =]