It is language spoken by fire elementals from the Firelands. It is also known by conglomerates with the sub-type of fire.  ( The half-elf banshee, )Ielephia also knew the language. (. Perhaps a dialect of )Kalimag.
The term Ignan shows up in the Kalimag phrase, "Ignan'kitch" in the Kalimag language parser.
"Ignan" has an apparent connection to DnD derived generic languages, which apparently can be found in DnD rule books.