Taint

A malevolent curse afflicting Giants. Approximately 15% of all young giants after emerging from their hibernation as adult giants become Tainted Giants instead of True Giants. Some become two-headed Ettins , some one-eyed Cyclops, some deformed Fomorians while others have one or more unique conditions.
Tainted Giants are shunned and even hunted down and killed by True Giants. Because of this, quite a few flee the giant lands in the north. Some even make it to Ettrea.
It was the demon Mastiphal who made the curse, possibly because of some rivalry with Annam.