This is a leg burner
4x8 Back squat ( 45 secs rest!) (50-60% of max! Not heavy!
2020 (2 Secs down, 0 bottom, 2 secs up, 0 top)

Keep flexion at the top of the squat! This keeps your legs under tension

Goal is to build deep muscle strength. Key is tempo and short rest periods! This should feel nasty in a good way.