If you wanted a cake and it called for eggs but didn't have any, you could use a proper amount of blood as a substitute because it congeals in the same way, with a very similar consistency. It won't work if the animal was taking blood thinners before death.
However, you cannot make meringue with blood because it would be like trying to whip an egg white with yolk mixed in. Rather than fluffing up, it will just blend.