Filinuvekta means “Winds From Darkness” in Falatacot.
The Filinuvekta is the Dericost faction controlled by the nobles of Dericost, most notably, Lord Rytheran, Lady Aerfalle, and their master and king Geraine IV, known as His Eternal Splendor by his followers. In terms of creatures we see on Dereth, Undead (liches) are for the most part Filinuvekta.
The Filinuvekta and the Latzimestal have warred for ages. The Filinuvekta were Dericost nobles and the secret leaders of the Ice Throne, and wished to continue to rule their kingdom in secret. The Latzimestal believed that as the generals of Dericost they controlled the true power of the Kingdom, and should be able to rule it as they saw fit - openly as undead.
See for references for example: The Book of Minesh.