One example I like from Krimm_Blackleaf's thread, posted under it by thebigb:
When he opened the large walk-in closet, he deeper in the closet a flickering candle on a little girl's tea table. A very old doll sat there, with no hair & its face full of cracks. After seeing the creepy sight, the player was very freaked when it opened its eyes. His character then proceeded to smash that doll into bits against the wall, then grab the little chair it was sitting on & smash all the other dolls. The dolls bled as they died, and another Listen roll heard the sound of babies crying as he smashed them.
It not only presents the creepy and unknown, but the overreaction/self-assurance of the player causes him to do what might be percieved as a horribly evil act. If the dolls were evil, having them be immortal or undefeatable would lead to rational fear, but horror is irrational fear. From evil's perspective, leaving the player with uncertaintity and dread is far more valuable anyhow. If the dolls were innocent, their tortured state that should bring the highest level of empathy is what brings them to more otherworldly torment: we could only hope he was putting them out of their misery, sadly this is unlikely.