Kekkei no Mahō
Bloodline Magic (血継の魔法, Kekkei no Mahō) is a type of magic just like Caster Magic and Holder Magic. Bloodline Magics are exclusive magics passed down in a specific family otherwise known as a clan. It is possible for a mage to use more than one magic if they are in more than one clan. It is just as easy for a mage to be unable to use any Bloodline Magics if they aren't strong enough even if they are in a clan.
Like Lost Magic, Bloodline Magic can come in many different forms. It can manifest itself as a Caster Magic, Holder Magic, both, or something else that can't necessarily be categorized. This gives Bloodline Magics the potential to highly versatile because they are not always limited to a certain function like how Fire Magic can only be used to create fire. This makes the users of Bloodline Magic, called Blood Mages, feared by all because it's impossible to tell what they are capable of.
There are a lot of advantages that come with using a magic born from one's DNA. Since Bloodline Magic is directly connected to the mage's DNA it cannot be controlled, nullified, copied, or absorbed by other mages no matter how strong they are. The only way a mage outside of the family can use the family's Bloodline Magic is by obtaining their DNA through an organ transplant or modifying their own DNA to perfectly match the family's DNA.