This rep scheme is called wave loading. The first 8-6-4-2 isn’t a warm up! The goal is in increase weight as you decrease reps and then match your first wave. We’ll aim to start our set of 8 at about 65-70% of our 1RM and end up with our set of 2 at around 90-95%. Then repeat. Take about 3 minutes per lift (1 minute to lift and 2 minutes to rest). You will need that rest so take it! Good luck!!