I think the reason is that at first glance the card is illegible, being a tangled mess of hard to make out shapes, and only on closer inspection it starts to make sense
The illustrator of much of the original artwork of the Pokmon video games, Sugimori is also the most prolific Pokmon TCG illustrator of all time, with almost 1,000 cards to his name
For example, the text of Valakut Exploration specifically says: You may play that card for as long as it remains exiled. The word play indicates that you can play lands that you exile with this ability
In black-border
These cards are relatively inexpensive, with many collectors speculating that theyre essentially free
Then put a creature, enchantment, or land card from among the milled cards onto the battlefield