The mighty monuments of the Giants are not the only legacy of the old empire hidden in the wilds of Xen'drik. The ancients crafted powerful magic as well. Artifaces like the Seven Swords of Sin have recently captivated the imagination of several explorers and chroniclers. But there are even greater magics hidden in the corners of Xen'drik - artifacts like the Shattered Star itself, said to be the first major creation of King Xen. Legendary founder of Sulatar. I believe the Shatter Start exists still. Its skymetal fragments scatters across Eberron waiting to be rediscovered.
- Val'trith d'Orien, They Grey Company Chronicles, Volume 22
Each shard comes with a curse that affects anyone who carries it. Even when the character ceases to carry a shard, the curse continues to affect him for another 24 hours. By placing an ioun stone of a specific type in the indentation in the shard, this curse is suppressed and the shard is activated. The ioun stone does not bolster the shard's powers in any other way, but continues to affect the person who carries the shard as though it were orbiting that person's head normally (even if the shard's carried in an extradimensional space like a bag of holding.
The caster level for the Shattered Star is unusual. In its current shattered state, the Sihedron draws its power from the creature that carries the shards, setting the caster level as equal to the owner's Hit Dice. All spell effects generated by a Shattered Star shard manifest at this caster level. For other effects, the shards have a caster level of 25th. Unlike other artifacts, the shards cannot be destroyed individually. Only by recombining them into the Sihedron and then using that artifact's method of destruction can one destroy the shards.
A character who carries three or more shards of the Shattered Star becomes sickened by the competing magical effects. A character becomes staggered with four shards, nauseated with five, stunned with six, and unconscious with seven. These effects can be negated for 1 minute if the character succeeds at a DC 20 Will save, but immediately manifest if the character continues to carry multiple shards beyond that minute.
Activating a Shard
Each of the Shattered Star shards bears a small indentation the exact size of an ioun stone. When an ioun stone of a certain type is placed in the indentation, the shard activates (see spoiler). The ioun stone is destroyed if removed, but otherwise grants its full benefits to anyone who carries the shard. As long as a shard has the proper ioun stone embedded in it, its curse is suppressed and does not affect the carrier of the shard.