The blood drums of Marosk'kro

These drums are ancient, build from ebony wood with taunt pergament hides drawn over their frame. Covered in ridges and nudges, similar to the storybones of Bar'kashyr, they sound and behave like any ordinary drum. Their inherent magic awakens once the drummer draws blood - be it his own or that of a foe, as long as the sacrifice comes from an intelligent being. The blood wavers and shifts, drawn to the ridges, where it pulses and dances with every beat that is cast.
In this state, the sound of the drum is entirely different - it booms with earthshaking force , drowning all other sounds for miles,leaving battlefields full of stumbling warriors in its wake, all coherence of once coordinated formations gone. And into this confusion the children of the steppes descend, all teeth and claw, to reap bloody harvest.