- The masked bending thief, who can appear seemingly out of nowhere and vanish just as quickly. Not helped by the fact the disguise is reminiscent of a Plague Doctor. Its like they were specifically trying to invoke this very trope. Even worse is the understanding that behind the mask the could be anyone... even those they might have considered friends...
- The walking dead arent exactly pleasant to behold either, whenever they appear the story instantly becomes much more serious. They cant be reasoned with or bargained, only fought or fled from, and they rack up damage but keep on fighting until totally reduced to ash.
- Korras nightmare about her four previous foes attacking her, then melting into black slime and re-forming into her new enemy, able to wield all four elements while she is powerless, all while Vaatu is taunting from the background.
- The Reveal about Temuji and Fumikos plans. To really and truly bring the dead back to life. Korra herself is horrified at the prospect, and declares that no one should have that sort of power. Whether or not they can succeed quickly becomes irrelevant.
Nightmare Fuel / Book 5: Legends