This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Kyoryu Sentai Zyuranger
Those who fail to answer Dora Sphinx's riddles correctly are trapped inside trees that are about to be cut down. Unseen and unheard, they can do nothing but scream as the tree they're in is being cut down.
Dora Goblin eating the souls of children
Dora Boogaranan swallowing Geki and Dan whole.
Bandora bleeding from her eyes while casting the spell to summon Dai Satan.
The moment in Zombie Franke's transformation into Satan Franke where his skull splits in half.
In Episode 20, just imagine being one of the children on that bus getting picked up and soon set up to go over the side of a cliff!