To kill a Unicorn is to bring bad luck and the hatred of nature itself down upon the foolish. It is said that the mate of a unicorn that is murdered will turn horrible in it’s pain and anger, turning against nature to hunt and kill the murderer of it’s mate. It turns dark and soulless and seeks nothing but the death of it’s enemy.
For a creation of the Black Tide of Acqua,death never truly befalls it. As long as the most vital part of it survives,the foul thing will continue to exist. In a certain sense..
Animals have parasites and diseases, so do plants, there are even bacteria that cann dissolve oil spills or plastic or what have you - why couldn't there be a disease living off magic - a magic item could be infected, losing power and speading the plague to other equipment it contacts, while a magic user would slowly lose his powers and contaminate all he works with or casts a spell at...