The Lux Foundation Library is a common Plane — The Library card from Doctor Who (WHO), collector number 588. Current market price: $0.45, TCGplayer market prices via Scryfall.
Players have no maximum hand size. Whenever a creature you control deals combat damage to a player, you may draw a card. Whenever chaos ensues, put a shadow counter on target creature. (A creature with shadow can block or be blocked by only creatures with shadow.)