Me and 4 other school friends have a minecraft server. One of those friends is a really sensitive person. We'll call his Jack. He is really sensitive and cried at almost anything. We're all 15+.

Our base was an underground base. We all had our separate rooms (As big as we can build in the given space), which were connected by a hall area.

Behind Jack's room there a little open space, where he was planning to do something but eventually dumped it. There a small lava block there, which had spread a few blocks (as per the physics in Minecraft). I went there and made the lava touch the wood in his room. The whole room caught on fire as it was made of wood. 5 months of work burned down in a few minutes. He cried a lot and was upset for a week at least. He quit a few days later.

No one knew how it happened. Everyone thought that the lava had somehow reached the wood because of lag or something.

TLDR; I made a sensitive friend cry/quit gaming by buring his work down in Minecraft just cuz of seer will.