The Adventures of Mark Twain from 1985 has a scene where Tom Sawyer, Huck Finn, and Becky Thatcher enter a sort of pocket dimension and meet a stranger who is just a robe holding a mask. The stranger claims their name is Satan. Satan creates a doll sized castle and gives the children clay to make people. After the people are made Satan gives them life and all 4 characters watch the clay people for a little while. Then Satan calls them insignificant, annoying, and worthless before he smashes some with his hand, lightning strikes other clay people, and the rest get swallowed up by a sinkhole along with the castle. While this is happening Satan's face/mask distorted and twists until it resembles a skull.

I saw this movie while spending a weekend at a family member's house as a kid, maybe somewhere between the ages of 5 and 7 (it was an old movie then). I woke up in the middle of the night and this movie was put on while I was left alone in the living room. I don't remember anything else from this movie, but it definitely fucked me up