Clues are artifact tokens created primarily through the investigate mechanic. A standard Clue can be sacrificed for two mana to draw a card, making Clue decks particularly good at turning piles of artifact tokens into long-term card advantage.
Academy Manufactor turns every Clue into an even larger haul of artifacts, Erdwal Illuminator can effectively double your first investigate each turn, and Eloise, Nephalia Sleuth keeps the evidence piling up whenever your creatures die.
