Jim Hawkins, Honorable Pirate Being able to filter the top four cards of your deck just by playing Jim Hawkins is fantastic
Even the basic lands are a few bucks and everything is over $1
Most of the time, it's worth giving your opponent a card for a copy of an instant, sorcery, or Otter -- that's because you get the copy for free and it's likely to be better than a random card from their deck
Pillar Analysis: High Power (Dual Land), Scarcity (Beta, Reserved List), Collector Scarcity
Creatures don't even need to actually deal combat damage for Hopper's ability to trigger, they just need to have been declared as attackers letting you Maze of Ith or Labyrinth of Skophos a creature to get them out of harm's way but still get that clue
K'rrik, Son of Yawgmoth allows you to pay 2 life for each black mana symbol in a cost