That happens to be exactly what this four mana Black Enchantment Artifact does, and we love it
Secondly, the same kind of permanent will get put onto the battlefield, so you get a bit more room for speculation: If you target an artifact, chances might be high that he gets a random mana rock in return
Blue, Loyal Raptor Compy Swarm Ellie and Alan, Paleontologists Grim Giganotosaurus Henry Wu, InGen Geneticist Ian Malcolm, Chaotician Indominus Rex, Alpha Indoraptor, the Perfect Hybrid Owen Grady, Raptor Trainer Permission Denied Ravenous Tyrannosaurus Swooping Pteranodon Dino DNA Plains Plains Island Island Swamp Swamp Mountain Mountain Forest Forest Command Tower Command Tower

Scientists Aang's Journey Abzan Monument Agency Outfitter Analyze the Pollen Archdruid's Charm Balamb T-Rexaur Beamsaw Prospector Bebop, Warthog Warrior Bedhead Beastie Beseech the Mirror Bioengineered Future Biomechan Engineer Biotech Specialist Black Chocobo Bloomvine Regent Borough Backup Brave the Wilds Brightglass Gearhulk Burnished Hart Bushwhack Call the Mountain Chocobo Campus Guide Canyon Crawler Caradora, Heart of Alacria Case of the Shattered Pact Case of the Stashed Skeleton Celestial Reunion Central Elevator // Promising Stairs Central Elevator // Promising Stairs Changeling Wayfinder Circuitous Route Cirina Bargainspinner Claim Jumper Clay-Fired Bricks Cloud, Midgar Mercenary Cloudbound Moogle Colossal Rattlewurm Compass Gnome Cool but Rude Cosmium Confluence Courier of Comestibles Cycle of Renewal Cynical Loner Daggermaw Megalodon Dance of the Tumbleweeds Dauntless Scrapbot Delivery Moogle Demolition Field Demonic Counsel Dina's Guidance Divert Disaster Dragonstorm Forecaster Earthbender Ascension Edge Rover Elemental Teachings Embermouth Sentinel Emergency Eject Emeritus of Woe Encroaching Dragonstorm Environmental Scientist Escape Tunnel Everything Pizza Evolving Wilds Expedition Map Fabled Passage Fang-Druid Summoner Fateweaver Fierce Empath Flourishing Bloom-Kin Formidable Speaker Fountainport Bell

I have absolutely no idea what most of these cards are, and that makes me love them even more
The process involves setting up a date and time and joining a video call where you show a store representative what you intend to sell