The Pulsating Worldstone Shard is dropped by Baal on Destruction difficulty. It is the key leading to the uber boss Samael, Herald of the End.
As you touch the crystal your mind is filled with fractured memories from long ago
"...and that is why neither of our brethren will find us here. We will forge a new world and our children will know peace."
*Transmute*
Once put inside the Horadric Cube and transmuted (with no other items), the description will change to the following (in this order):
"A Sanctuary, forevermore. Free from the Eternal Conflict and the dangers beyond the Veil."
"The Veil? Inarius surely you haven't succumbed to Itherael's prophecies... nothing more than an attempt to explain the unfathomable."
*Transmute*
"The Stone has been, is, and will be the axis of our worlds. What came before is irrelevant!"
"Lillith... the High Heavens, Burning Hells, Sanctuary. These worlds, dimensions, are but a grain of sand in the universe."
*Transmute*
"There are many more worlds than those upon which we have stood. The Worldstone has existed since the Dawn of Time and kept us safe in the sea of possibilities, yet we can't be sure what lurks just beyond our understanding."
*Transmute*
...
"Lillith... the High Heavens, Burning Hells, Sanctuary. These worlds, dimensions, are but a grain of sand in the universe."
The destruction of the Worldstone has not only exposed Sanctuary to the direct influence of Heaven and Hell. It has exposed to us all to an even greater threat.
This shard is the key, its full potential must be unlocked.
*Transmute*
It which bears the writings of genesis
It which can manifest their son and his disciple
It which is of the brother, savior and sacrifice
It which is of many and may cleanse the soul
It which is the splinter of the spirit in a land Unformed
At this point, the Pulsating Worldstone Shard must be transmuted with the following charms and unique items:
- Sleep
- Ring of Virtue (void quest)
- Neutrality Pact
- Assur's Bane
- Ghost Trance
Its description will then change to the following:
The Worldstone crystal has been reforged
It must now be imbued with Knowledge and Arcana
Greater Signet of Learning
Taha Great Rune
Transmuting the Pulsating Worldstone Shard with a Greater Signet of Learning will create a Dimensional Link, which opens a portal to the Edge of Nothingness, Samael's lair, if used in Act 5 Hell difficulty. The Pulsating Worldstone Shard itself is not consumed by this recipe.