Both are pretty standard card advantage engines, though they go about earning you value in very different ways
Combine it with cards like Arcane Adaptation (which changes the type of every creature you control to another of your choosing), and you can easily start locking players out of the game

Advanced Search Sets Random Syntax Abundance Agent's Toolkit Alhammarret's Archive Alms Collector Archive Haunt Archmage Ascension Artist's Talent Asmodeus the Archfiend Bard, King of Dale Blood Scrivener Breathstealer's Crypt Case of the Pilfered Proof Catlike Curiosity Chains of Mephistopheles Chronomancer Combat Courier Cryogen Relic Dakmor Salvage Dark Dabbling Darkblast Dennick, Pious Apparition Don't Blink Enduring Renewal Equal Treatment Eruth, Tormented Prophet Family's Favor Fasting First-Sphere Gargantua Fisher's Talent Flotsam // Jetsam Flotsam // Jetsam Forbidden Crypt Golgari Brownscale Golgari Grave-Troll Golgari Thug Grave-Shell Scarab Greater Mossdog Hallowed Moonlight Heroic Sacrifice High Score Hullbreacher Immortal Coil Island Sanctuary Izzet Generatorium Jace, Wielder of Mysteries Jaya Ballard Laboratory Maniac Laboratory Maniac Lashknife Barrier Leader, Super-Genius Lich Life from the Loam Living Conundrum Loch Mare Magus of the Chains (playtest) Mangara's Tome Mawloc Meat Locker // Drowned Diner Meat Locker // Drowned Diner Moldervine Cloak Necrodominance Necroplasm Nemata, Primeval Warden Nightmare Void Notion Thief Obstinate Familiar Ormos, Archive Keeper Out of the Tombs Ozolith, the Shattered Spire Parallel Thoughts Peregrin Took Personal Decoy (playtest)

Cards that are likely intended for display or collection tend to sell more than those used for actual gameplay, and this trend has been increasing, they say
Pokmon cards are collectible, sure but they are also the base of a competitive strategy game played by millions