There is, in fact, a full cycle of these lands--one for each color
Its an odd card, but despite it seemingly being way too expensive, its actually normally only going to cost you one mana, because its one generic mana cheaper for each Creature on the battlefield
Sure, they get sacrificed at the end of turn, but do you care when a pile of Combustible Gearhulk copies, or Inferno Titan duplicates, already left your opponents in ashes

Release date: 2009-09-04 Academy at Tolaria West Akroma's Vengeance Congregate The ther Flues Agyrem Kor Sanctifiers Bant Oblivion Ring Cliffside Market Orim's Thunder Prison Term The Dark Barony Eloren Wilds Soul Warden Broodstar The Eon Fog Fabricate Feeding Grounds Fields of Summer Keep Watch Master of Etherium The Fourth Sphere Glimmervoid Basin Qumulox Goldmeadow Sarcomite Myr The Great Forest Thirst for Knowledge Grixis Vedalken Engineer The Hippodrome Whiplash Trap Ascendant Evincar Immersturm Beacon of Unrest Isle of Vesuva Beseech the Queen Izzet Steam Maze Cadaverous Knight Krosa Consume Spirit Lethe Lake Corpse Harvester Llanowar Cruel Revival The Maelstrom Dark Ritual Minamo Death Baron Murasa Dregscape Zombie Naar Isle Festering Goblin Naya Grave Pact Otaria Gravedigger Panopticon Helldozer Pools of Becoming Hideous End Raven's Run Incremental Blight Sanctum of Serra Innocent Blood Sea of Sand Nefashu Shiv Noxious Ghoul Skybreen Phyrexian Arena Sokenzan

How Does Delirium Compare with Threshold