Blood is an essential and integral part of every living organism. Disrupting the flow of blood or infecting the blood itself is enough to affect the being's vital functions. It is for this reason that blood abilities have emerged, giving the upper hand in battle.
Blood abilities can be used by regents, and they are either offensive or defensive, just like the spells. Controlling them gives you a great advantage over your opponents. But what if you could select the blood ability by yourself?
It was not long enough till the regents came up with the solution and created the blood ability known as the Blood Master. This ability can do exactly what you thought about - by using it, you can select the desired blood ability by yourself!
The Blood Master is a rare ability that is not known very widely. However, it is considered to be one of the most dangerous abilities among them all. If you ever come across a player that have the Blood Master - prepare for the worst.