Even if you don't have the creatures to charge it, its enter trigger lets you search for a legendary creature and put it into your hand
Whether you choose to actually sell it is up to you

Barrow Naughty Barrowgoyf Basilisk Collar Basri's Acolyte Basri, Tomorrow's Champion Batterbone Batterskull Battlegrace Angel Behemoth Sledge Beloved Princess Benalish Partisan Betor, Ancestor's Voice Bishop's Soldier Black Panther, Claws of Bast Blacklance Paragon Bleeding Effect Blessed Defiance Blessing of Belzenlok Blood Baron of Vizkopa Blood Burglar Blood Glutton Blood Operative Blood Poet (playtest) Blood-Cursed Knight Bloodline Necromancer Bond of Discipline Bonepicker Skirge Boon-Bringer Valkyrie Boot Nipper Boros Mastiff Brave Brawler Bre of Clan Stoutarm Breathless Knight Bretagard Stronghold Brightblade Stoat Brightling Brion Stoutarm Brisela, Voice of Nightmares Bruse Tarl, Boorish Herder Bruse Tarl, Boorish Herder Butcher of the Horde Butcher's Cleaver Butcher's Glee Cabal Initiate Caduceus, Staff of Hermes Cairn Wanderer Call the Bloodline Call to the Feast Captain America, Steve Rogers Captain Marvel, Earth's Protector Caravan Hurda Cartouche of Ambition Case of the Gorgon's Kiss Cat Cat-Gator Cavalier of Night Cecil, Redeemed Paladin Celebr-8000 Celestine, the Living Saint Champion of Arashin Champions of Tyr Chancellor of the Dross Changeling Hero Charismatic Conqueror Charity Extractor Charmed Stray Child of Night Chromanticore Circle of Power Citizen V, Helmut Zemo Civil Servant Cliffrunner Behemoth

Alongside their pricing history, Ill explain why each one has a permanent spot in my collection