Jade being tortured by Lung until she goes completely insane, and then her astral form melts.
At one point during said torture, her eyelidsdissolve.
Jade's PTSD from the above is starting to reach this level, particularly the Freak Out she has when Tohru accidentally recreates the situation — she reduces to an almost animalistic state, and ends up slashing Tohru in the face.
Though they're disposed of easily enough, the monsters in the Vault of Endless Night are pretty horrifying, especially when it's hinted that there are things far worse even farther down.
The scene where Jade brainwashes Viper and turns her into the Samurai General is pretty horrifying, and it's made even more so by the fact that the PTSD mentioned above has caused her to completely snap.
Apparently the cult that trained Blankman worshiped an entity implied to be the Slender Man (which Blankman apparently kills)!
Hak Foo laying waste to San Francisco with the Mini-Khan is played a lot more darkly than in canon.
When the J-Team is recovering the final mask from underwater, Jade stalks them in the form of a giant snake from beneath, while shrouding them in darkness, attacking their boat and scattering them. She then isolates Tohru and Uncle on an islet and attacks them repeatedly until their chi defenses are broken down. If not for Tohru's latest 11th-Hour Superpower, she would have killed them both right there.
The latest glimpse into Jade's mind shows that Paranoia has now almost completely usurped control of it all from the Queen, shrouding it all in darkness and putting the Queen on the defensive.
And during the Final Battle, it's revealed that the Queen has been reduced to a literal puppet under Paranoia's control. And even after Paranoia is destroyed by having Kaito's chi removed from Jade by Tarakudo and the Queen is restored, she's left completely berserk, even turning into a shadow monster to fight Hero and Father.
Jade has gone completely murderous towards Tohru.
The first part of the finale ends with Right stabbing Jade.
The description of Jade's wound after Tohru heals her, which was extremely unpleasant.
Blankman putting a circlet of recently molten metal on his head, which is only slightly lessened by the fact that the Horse talisman is immediately healing him.
The implication that the failure of the Design is starting to cause seals to spontaneously fail...