This spell requires a large black gem-stone of any kind worth at least 5,000 gp and a functional ioun stone of the spell-absorbing, ellipsoid variety. When the spell is cast, the ioun stone is drawn into the gemstone, thus creating the blackstone. Once done, the blackstone is capable of absorbing magical energy from any source, be it a spell, spell-like power, or magical device. Such energies cast directly upon the blackstone are instantly absorbed. Likewise, if the blackstone is within the area of effect, magic is absorbed without any effect. If the blackstone is brought into an active area of effect (e.g. a previously cast continual light, airy water, etc.), touched to the surface of a magically created barrier (e.g., a wall of force, shield, prismatic sphere, etc.), touched to a creature or object affected or influenced by magic (e.g., charmed or summoned creatures, held doors, a caster with active detection magic etc.), or comes in contact with any magic controlled from afar (e.g., the various Bigby's hand spells, Tenser's floating disc, etc.), the contacted magic is absorbed. This absorption does not affect the enchantments of permanent items, such as rings, armor, weapons, etc., but if such a device can release a magical effect (e.g., a sword releasing a fireball, etc.), the effect is absorbed if the blackstone is within the area of effect. Likewise, it does not drain charges from items like a magical staff or wand, but released effects of those devices are absorbed.
All spells, spell-like abilities, and magic effects are absorbed if employed by anyone carrying or touching the blackstone.
If detect magic or similar magic is cast on the blackstone, the caster will see a sudden “flash” of magical power before the divination is absorbed. Identify and other property-revealing spells show the caster only that it can absorb magic before that magic is itself absorbed.
While the blackstone may seem useful at first, it is typically used as a trap for greedy treasure hunters, offered as a “gift” to rivals, or placed so to be found by an enemy. In fact, the blackstone is quite baneful to its owner, especially if the user thinks it a defense against magic or probes it too much with magic.
The blackstone can absorb a number of spell levels equal to the ioun stone used in the blackstone's creation, regardless of the comparable level of the effect (the blackstone does not have the spell-level limits of the ioun stone in this regard). Thus, if the ioun stone was able to absorb 14 spell levels before burning out, the blackstone can absorb 14 spell levels. If this number is ever exceeded (absorbed energy cannot be safely released or negated to allow continued spell absorption), the energy is absorbed, but the blackstone instantly explodes in a wave of raw magical energy.
All creatures within 60' of the blackstone suffer 1d4 hp damage per spell level absorbed (including the excess levels that caused the explosion). A save vs. breath weapon reduces the damage by half, but all inanimate items within the area (including carried items) must save vs. disintegration or be destroyed. Any creature actually holding the blackstone when it explodes suffers a -4 penalty to the saving throw.