The name rang a bell and indeed, it's a dragon/serpent in the Hittite version of the eternal battle between a storm god and a chaos beast.
Anything related to that part of mythology, beginning with "ill", "wal" or "yl" I always have to check. I'm no etymologist so I'm most often wrong, but any language relations between the Hittites and the Tocharians/Yuezhi would be most pleasant and could be used in some way. (in Oak and Thunder)
Alas, it was another case of me getting too excited over nothing. :-D Illuyanka is in no way related to Ylaiňakte. In fact, despite Hittite being an isolated branch of the IE language family, this is a case of the typical naming tradition for the storm god and his serpent.
Illuyanka is probably a compound, consisting of two words for "snake", Proto-Indo-European *h₁illu- and *h₂eng(w)eh₂-. The same compound members, inverted, appear in Latin anguilla "eel".And of course, his opponent is Tarhunt/Teshub:
Teshub (also written Teshup or Tešup; cuneiform dIM) was the Hurrian god of sky and storm. He was derived from the Hattian Taru. His Hittite and Luwian name was Tarhun (with variant stem forms Tarhunt, Tarhuwant, Tarhunta), although this name is from the Hittite root *tarh- "to defeat, conquer"Just as with Ylaiňakte (= Indra/The Smiter), Tarhun means "conquerer", the PIE root is even the same as with Thor and other IE thunder gods and smiters. (the meaning "smiter/conquerer" is also the same in the Iranian god - "Verethragna")
Taranis, as a personification of thunder, is often identified with similar deities found in other Indo-European pantheons. Of these, Old Norse Þórr, Anglo-Saxon Þunor, Old High German Donar—all from Proto-Germanic *þunraz (earlier *þunaraz)—and the Hittite theonym Tarhun (see Teshub) contain a comparable *torun- element. The Thracian deity names Zbel-thurdos,Zbel-Thiurdos also contain this element (Thracian thurd(a), "push, crash down"). The name of the Sami thunder god Horagalles derives from Thor's.
All in all, nothing new under the sun, no exciting connections to explore. The Tochari are still weird and isolated.