Vicion, the Viscerator

When Vicion, the Viscerator enters the battlefield, choose a creature type. Destroy all creatures of the chosen type.
Whenever a player casts a creature spell, destroy target creature other than Vicion that shares a creature type with it.
Stories rarely mention Vicion, but her bloody frenzy has raged for millennia, acknowledged only in deep fears that shall never be pressed in ink.