You alter the nature of one weapon and imbue it with the ability to petrify those it strikes. Although the base damage of the weapon is unaltered, the weapon deals bludgeoning damage for the duration of the power.
If a creature struck by a weapon affected by blackstone hammer fails its saving throw, it (along with all its carried gear) is turned into a mindless, inert statue of dark stone. Striking a creature with the weapon discharges the power. If a statue resulting from this power is broken or damaged, the subject (if ever returned to flesh) has similar damage or deformities. The creature is not dead, but neither does it seem to be alive when viewed with spells such as deathwatch.
Only creatures made of flesh are affected by this power.
For every 4 additional power points you spend, you can invest the weapon with an additional charge. Each additional charge allows the weapon to be used one more time before the blackstone hammer effect is discharged.