From D&D Wiki
|This material is published under the OGL 1.0a.|
Throw this stone as a grenadelike weapon. When it strikes a hard surface (or is struck hard), it creates a deafening bang (a sonic attack). Creatures within a 10-foot radius must make Fortitude saves (DC 15) or be deafened. Deaf creatures, in addition to the obvious effects, suffer a -4 penalty on initiative and a 20% chance to miscast and lose any spell with a verbal (V) component that they try to cast.