creating bloodlines

in my game the players found a mystical old book , in that book describes the secret of creating bloodlines, how works and how you can do it.

i always wanna try this in my games.

the real problem is : the bane , i mix the 2 banes? how i can create a new bane?

you guys have any ideas or a recipe to create any good bane doesn't matter what clans my players wanna to mix toghther to make the new bloodlines