Book collecting has long encompassed more than what is implied by a narrow interpretation of the word book. It has included other bound paper items, such as booklets, pamphlets, magazines, catalogues and brochures, along with unbound paper items such as manuscripts, maps, newspapers, letters, prints and photographs
Browse by set (151, Twilight Masquerade, Surging Sparks, etc.), by rarity (Illustration Rare, Special Illustration Rare, Ultra Rare), by type, or by individual illustrators like Mitsuhiro Arita, HYOGONOSUKE, and others
A Putrid Imp is the "best" discard outlet from a pure combo perspective
Recently it popped up to $10 and came back down, but the really impressive growth was in the foil that went from $15, doubled briefly to $30, and is back in the $22 range
It could further be limited to copying things based on their mana cost ones and twos, for example, as a way to build whites existing body of caring about efficient, cheap spells