It's the Blackblade itself
Kodama of the East Tree Cheating cards into play significantly increases the power of tutors and card draw, and if you have the mana to cast Kodama of the East Tree, you can put down two cards on a turn when you should have been able to afford one
The gray circle represents a Common card, the white book represents an Uncommon card, the bronze triangle represents a Rare card, the silver diamond represents a Super Rare card, and the gold pentagon represents a Legendary card
It wouldve been annoying to play against in grindy games from the early years, though
(There are 49 total art cards, with a regular art card found in 30% of boosters and a foil-stamped signature art card in 5%.) Many cards, art cards, and other Play Booster elements contain clues for the 13 puzzles across Murders at Karlov Manor products
It's true in that they usually fail to convince people of their argument (because it's wrong), but people are likely to interpret it as them suffering some negative consequence