Going that route is obviously easier if you have access to Wheel of Fortune and/or Memory Jar, but even without them, you can pull off a nice chain, especially with a copy of Underworld Breach and a card like Mana Geyser
On the secondary market, the price can spike a lot
For example, if you play a Mountain and your chosen number is 2084750930, you'd only be able to cross out one of those zeroes
This is one of the easiest things to look for when checking older cards (though to see the dot patterns properly you'll probably need to pick up a jeweler's loop)
Includes many character cards that deliver amazing effects with the Leader cards
Any deck that wants to cheat big creatures into play and doesn't care much about typal synergies can give this a look, as can any deck that can reuse its enters ability to get another double helping of cards to hideaway