Sealstone

The Sealstone was the massive physical reflection of the "Depths" Seal, a huge block of nearly unbreakable obsidian beneath the Pandoran Mountains. While the Seal was intact, the removed fragments of the Sealstone possessed a mysterious link with Tiamat's power, which could be used in magic and enchantment to channel some of her power. When the Sealstone was destroyed most of its fragments were depowered, severed from Tiamat and her corrupt World-Self. However, the resultant explosive release of Tiamat's power did contaminate five small chunks of Sealstone, permanently imbuing them with unusual properties. These stones have recently resurfaced and are wreaking havoc on a small isolated island nation.