Moses does his trick turning his staff to a snake for pharaoh. His magicians copy it.
Aaron brings about plague number 1, water of the Nile turned to blood. Undrinkable. The magicians can also produce red water.
It’s so personally about Pharaoh. His heart. God says it will be hard and it is. If you’ve ever wondered whether God couldn’t just force people to believe, remember this. The world’s most reluctant convert.