Guild Wars 2

I was looking at the guild wars official wiki page and I found “Superior Rune of the Nightmare” which is perfect for my Engineer build BUT I cant find it any where on the game. Can someone please let me know where to find it, if it even exist? The link for the rune is below:

http://wiki.guildwars2.com/wiki/Rune_of_the_Nightmare

The answer is right there on the wiki page you linked: You get them from the Twilight Arbor reward vendor in Lion’s Arch. Get TA tokens by running the dungeon and buy the runes with them.

Thank you! I can’t believe I missed that