Ilzak is possibly a location in Zakizga in world of Daventry. A kind of sauce, called Ilzak sauce is named after it, the sauce is used to flavor humans in one of their recipes.
Behind the scenes[]
It's not clear what the Ilzak is exactly. The term is spelled with a 'capital' "I" followed by a lower case 'l'. Although this is not clear in the font used here on this wiki.
It could be a place/region/city where the sauce originated, and home of Zuzak in Zakizga.
It could indicate rather a specialty dish, or the name of the imp who created the sauce in the first place (however the latter is unlikely as it is established that it is Zuzak's own recipe, and one that he is very protective of). So it at least was likely named by Zuzak.
On the other hand it might simply be a impish vegetable or herb of some sort. lizak (note with and an i) is a word for lollypop in the Polish language. The only known ingredients given in the story is a lquid, a green powder, and a yellow root vegetable of some sort.
It could be a race, however, it is worth noting that other races mentioned in the novel are not capitalized (other than the 'Laburnum' in almost all cases, which appears to be a special case since the book gives the creatures almost mythic/mysterious scope). Neither are other vegetables or herbs mentioned, ever capitalized.
Some references to the original Ever Quest appear to suggest that 'Ilzak' is the name of a lizard race (aka Iksar) similar to the Lizard Folk. However, "Ilzak" may just be a typo of word "Iksar" in those lists. If there is a connection perhaps the Lizard folk and the Ilzak are one and the same species.