The Neo-Soviet marine biomods
Greentails, sirens, mermaids, merfolk, the creature you think of when you hear these names is a Tangaroa.
Ten powerful magic rings created by an Archmage have scattered to ten random people (suggest only one is PC). This happened when he died in battle. Whoever gets all ten rings inherites all the power the Archmage invested to them over his 200 year life.