Enacting permanent change is not easy; most magics, whether divine, psionic, or arcane, must attempt to slowly change things over time, having to labor and stay in one place for quite some time for the magic to take hold. In this regard, physical labor and concerted effort is often superior; while a wizard can conjure a stone wall in ten minutes, a group of stone masons and architects can construct a fortification in a few hours. The yuan-ti of the Ss’Tkar’Jsona have looked to circumvent that with blood magic.
Fueled by Crimson
Before the Cataclysm, life and magic were distinct, separate entities. After the cataclysm, that changed. The Weave of Magic runs more tightly through all that walk the world; and, more importantly, it ties itself within their blood.
To understand what blood magic circumvents, you must first understand a little bit about how the Weave works: It is the fabric of the Universe that keeps all the planes held together, binds your feet to the ground, and keeps the world in motion. Changing anything through the weave requires highly specialized skills, and often can only alter the world in very specific and minute ways. Even then, these changes are usually temporary; the Weave always returns to normal.
Blood magic circumvents this; instead of altering or pushing on the Weave, blood magic blasts out and destroys the Weave that runs through living creatures, reshaping that energy into something new. Like bloodmarks or binding rituals. Because of this, blood magic is limited only by the amount of blood you have available, and is quite, quite dangerous in the wrong hands.
The Weave has its own limit, however, and some things might be out of reach even for blood magic….or the cost might just be unimaginably great. The Weave always returns to normal.