Glyph of Nightmares provides the warlock water walking when using their class mounts. However, unlike any other form of water walking in the game, you can still stay mounted and keep running on water while taking damage. All other water walking is buff based (DK's Path of Frost, Priest's Levitate, Shaman's Water Walking, Hunter's Surface Trot, Elixir of Water Walking) and the buff is removed when damaged, but this glyph provides passive functionality based on mount and without any buff. The reason this works is because they changed it in Wrath that players can't dismount other players. This makes it one of the best PVP minor glyph in the game currently.