Sillitta Ederus (halfling wizardess)- I utter a quick detect magic spell and move forward to get a better look at the throne, constantly glancing back to make sure a burly member of the group is with me.
Where are peoples sense of adventure. Sit on the thrown and then throw a dagger at the Paladin to satify the cry of the stones. Wait to see what happens next.
Greet any unseen inhabitants of the room in the languages I know. Be disappointed when I get no response. Shoot an arrow or other trivial costing missile weapon at the Throne of Bone. A joke with then be made about needing to use mana, not arrows to tap the Throne of Bone. A crude joke involving the word bone may also spoken. By this time someone in the party has walked into the room and triggered the encounter.
My Ranger (also named El Mahdi) fires a blunt, hollow bulb tipped arrow (filled with Oil of Impact) at the Throne. Whether or not the Throne is damaged, the Rogue who used stealth to sneak up behind the throne (unbeknowst to the rest of the party, of course) will need to make a save because of the ensuing explosion.