The Serpent Scale Shield is a difficult piece of equipment to acquire in Valheim. You will need to harpoon a few Sea Serpents to make one because their scales don’t float. The serpent scale shield is a tower shield and you cannot parry with it.
However, it has a lower movement speed penalty than other tower shields. This shield fits between the Iron Tower Shield and Blackmetal Tower Shield in terms of strength.
Serpent Scale Shield Statblock
Serpent Scale Shield Upgrade Table
For more info on how blocking works, check out the Blocking page.