I’m not sure about a pharaoh’s tomb, but there were rivers of mercury in the tomb of the first Emperor of China; also automatic crossbow traps I believe. It’s the tomb with the Terracotta Army. Extremely fascinating.

1. https://www.futura-sciences.com/en/this-tomb-is-a-deadly-trap-archaeologists-still-refuse-to-open-it_17867/

2. https://www.labrujulaverde.com/en/2020/01/rivers-and-seas-made-of-mercury-inside-the-tomb-of-chinas-first-emperor-sealed-2200-years-ago/