W.B. Yeats: This was brought up in a discussion about the Key of the Twilight, but it's really a fantastic work that deserves its own topic. Generally speaking, the poem is about a world populated by sprites who do not cast shadows, that is attacked by the Cursed Wave. Two half-sprites and one human girl--the "shadowed ones"--undertake a quest to find the Twilight Dragon and save the world. Though the phrase "Key of the Twilight" doesn't appear anywhere in the poem, the concept is similar to the Twilight Dragon, and though The World doesn't quote the poem often, there are many indirect references. For example, Delta Hidden Forbidden Holy Ground contains an area that could be said to be "Alba's Lake," where Apeiron King of Light and Helba Queen of Dark join forces to combat the Wave. Helba, of course, is also the name of a famous hacker. It is believed she based her name off of the Epitaph character.