Pumping mana into Triassic Egg eventually lets it hatch and summon an 'ancient creature'
While most decks would much rather tutor a card to their hand, there are plenty of decks that thrive off of getting a powerful card into the graveyard and then using something to let them get that card on the battlefield or stack way ahead of schedule

Most valuable cards in Adventures in the Forgotten Realms View the full price guide $72.77 Old Gnawbone Adventures in the Forgotten Realms $50.77 Old Gnawbone Adventures in the Forgotten Realms $48.31 Tiamat Adventures in the Forgotten Realms $24.76 Tiamat Adventures in the Forgotten Realms $16.02 Lolth, Spider Queen Adventures in the Forgotten Realms $15.06 Circle of Dreams Druid Adventures in the Forgotten Realms $14.12 Circle of Dreams Druid Adventures in the Forgotten Realms $14.03 Teleportation Circle Adventures in the Forgotten Realms More cards by Ilse Gort $35.04 Ajani, Nacatl Pariah // Ajani, Nacatl Avenger Modern Horizons 3 $25.14 Tasha's Hideous Laughter Adventures in the Forgotten Realms Promos $23.10 Ygra, Eater of All Bloomburrow $20.94 Appa, Steadfast Guardian Avatar: The Last Airbender $20.08 Ajani, Nacatl Pariah // Ajani, Nacatl Avenger Modern Horizons 3 $15.06 Yoshimaru, Ever Faithful Neon Dynasty Commander $10.96 Yoshimaru, Ever Faithful Neon Dynasty Commander $9.42 Pyromancer's Goggles Secret Lair Drop SetAdventures in the Forgotten Realms Most valuableTop 100 Magic: The Gathering cards You might also like...

Although you can't play with numbers as big as you can in stocks and real estate, the barrier to entry is tiny (even a 8-year-old kid can come up with the money to buy some under-valued Pokemon cards) and the potential for profit is huge
Three mana is more than you'd usually want to pay for this sort of ability
Krenko, Tin Street Kingpin becomes Makari the Lucky Grot in Secret Lair Drop: Warhammer 40,000: Orks