Ōin

The is an artifact that belongs to Soul Society's Royal Family, and is moved from its storing place to another every few decades.

Summary
When the Ōin was being transported to a new location. Sōjirō Kusaka and his two Arrancar companions attacked the transport and stole the artefact, despite 10th Division captain, Tōshirō Hitsugaya, guarding the transport. Later on Kusaka tries to get Hitsugaya to stab the Ōin with his Bankai, so its power would be released, but Hitsugaya refuses and Kusaka himself cuts the artefact. Because of this, Kusaka turned into a large, powerful ice dragon, but very unstable due to Kusaka not having achevied Bankai. It took the effort of several captains and Ichigo Kurosaki, but Kusaka was eventually defeated. Afterwards the Ōin was returned to the state it was in prior to being cut by Kusaka.

Powers & Abilities
Dimension Control: If a person has full control over the Ōin, then the person has absolute control over the dimension as they see fit, including the manipulation of time, energy, space, and matter.

Teleportation: Given that the seal can manipulate space, it can give the user the ability to teleport any amount of distance.

Healing: Given that the seal can manipulate time, if the user is hurt, they can transfer their body back to the way it was any time before

Requirements: For a person to fully control the King's Seal, they need to have the power of a Bankai. If they haven't achieved this, the seal's power will expand at a dangerous rate and cause mass destruction.