Spill 500 buckets of blood on Kratos
Enemies will frequently bleed when they are attacked or killed. Whenever some blood is spilled on Kratos it will count towards the 500 buckets required for the trophy. There is no way to track just how much blood he has accumulated but there is no need to worry, the trophy will unlock through natural progression of the game. If you spend extra time farming orbs during the tutorials in Chapter 1 and Chapter 5, or getting the Maybe you should call a Doctor? trophy, you will most likely unlock it during the Fire of Ares tutorial. If not, it should unlock somewhere between Chapter 6 and 8.