A Lockstone was a magical gem that triggered a few set spells when certain conditions were met. They were commonly used as wards and traps.
The Lockstone was thought to be native to several Outer Planes. They were quite rare.
A Lockstone typically resembled an orb or egg fashioned of crystal or metal.
A Lockstone could store up to three spells that would be triggered if up to two predetermined conditions were met. Once these spells were cast, the stone would turn dormant for a year, but would reactivate after that time, with the same function as did before.
The spells and conditions of a Lockstone could only be set or altered by a high-level wizard.
Lockstones were commonly used to ward valuable treasures and to trap extraplanar beings.
Prior to the 1350s DR, only three Lockstones were ever reported in the North.The extraplanar being Imgig Zu somehow employed a Lockstone to trap the fire elemental Jogaoh on the world of Abeir-Toril, having transformed the elemental into the form of a dwarf and withered his limbs with the staff of withering. Imgig Zu then placed the Lockstone atop Stoner's Needle in the Sword Coast lands with a frozen greater basilisk guardian. However, the Lockstone also proved the key to Jogaoh's release. Its conditions were the passing of two centuries and to be touched by a living creature. Once these were met, it would restore withered or lost limbs to the one who touched it and transform them back to their original form, but also awake the greater basilisk guardian. Jogaoh feared the basilisk too much to make the climb up and take the Lockstone. It resembled a large pink crystal egg.
When Vajra Valmeyjar, Cybriana, Timoth Eyesbright, Onyx the Invincible, and Priam Agrivar sought out Jogaoh in the Year of the Prince, 1357 DR, he agreed to help them provided they retrieved the Lockstone from atop Stoner's Needle, though he was evasive as to the details. Vajra, Priam, and Jogaoh ascended the rocky tower, where Jogaoh revealed his story. He took the Lockstone and was restored to his fire elemental form, then returned to the planes before the basilisk awoke to attack Vajra and Priam. Vajra slew the basilisk, using the reflection of the gem so it would turn itself to stone.