First King's Blood

When Ishurad Rainhald became the First King of Sanroth, he was given incredible power by the gods in order to unite the country and free it from the chaotic influence of Achaeron. These powers became infused within Ishurad's blood and so were passed down to his descendants after his eventual death.

However, the power of the First King became split across all those who carried his blood and so, over the generations, the bloodline of the First King became weaker and weaker and his descendants grew in number. By the time of the Hollow War, most members of the royal family possessed but a remnant of Ishuard's power. 
When Vimis Underdrey learned that he possessed the bastard blood of the First King, he became plagued by visions and nightmares and eventually enacted a plan to supposedly save Sanroth. He marched on the Great Keep and massacred the royal family in an attempt to consolidate the full power of the First King for himself. However, Damon Rainhald was able to escape, leaving the First King's Blood and all that associated power still split between the two.