Zeflmin Werlikanin says 'Hello ______. Come to take a look at the crystal geode? The geode has some very strong magic inside of it that can help you. I can bring out the magic of the geode for you, but a gnome has to make a living! Even if he's stuck in this little hole in the wall all the time. Not that I'm bitter. Each of the crystals I sell is linked to a location in our world. If you give me one of the crystals I can focus the geode to let you and your companions travel there in the blink of an eye!'
Purchase one of the crystals he sells and give it back to him.
Arcstone Spirit Sapphire - Arcstone
Broken Timestone - Plane of Time A
Chipped Shard of Slaughter - Wall of Slaughter
Chunk of Argathian Steel - Argath
Cloudy Stone of Veeshan - Plane of Sky
Crystallized Dream of the Feerrott - Feerrott, the Dream
Dragonscale Faycite - Dragonscale Hills
Drowned Katta Castrum Powerstone - Katta Castrum: Deluge
Etched Marble of Barindu - Barindu, Hanging Gardens
Forest Emerald of Faydark - Greater Faydark
Fragment of the Combine Spire - Lceanium
Frozen Shard of Iceclad - Iceclad Ocean
Fuligan Soulstone of Innoruuk - Plane of Hate
Goru`kar Mesa Sandstone - Goru`kar Mesa
Grassy Pebble of the Commonlands - Commonlands
Karana Plains Pebble - North Karana
Katta Castrum Powerstone - Katta Castrum
Lavastorm Magma - Lavastorm Mountains
Moss Agate of Stonebrunt - Stonebrunt Mountains
Opal of Toxxulia - Toxxulia Forest
Shadowed Sand of the Twilight Sea - The Twilight Sea
Shattered Bone of the Dreadlands - Dreadlands
Splinter from a Guild Standard - The location of your guild's banner
Stone of the Shard's Fall - Shard's Landing
Stormstone of the West - Ethernere Tainted West Karana
Velium Shard of Cobalt Scar - Cobalt Scar
Undershore Coral - Undershore
Unrefined Brellium Ore - Brell's Rest
Zeflmin Werlikanin takes the crystal from you and mutters some arcane words over it. 'The crystal geode is now active, just go step on the crystal platform and you'll be whisked away to your destination! I hope you don't get motion sickness!'
The crystal geode is now set to teleport you to the location you picked. Note that this will reset if someone else turns in a different crystal or the instanced Guild Hall goes away after no one has been in the instance for a while.