The librarian is eating books with the assistance of some library paste in a hilarious, flavorful depiction of the cards ability
They are worth buying as a long term sealed product hold if you buy retail, choose wisely, store properly, and think in years rather than months
While it doesn't quite work as a graveyard recursion commander due to the lack of green in its color identity, it fits excellently into the 99 of many strong Orzhov (white/black) decks
The best we've used has been the Vault-X so far
It doesn't say once per turn, but because of the restriction that you can only attack with the equipped monster, it is effectively once per turn (you can't apply the same restriction to multiple monsters & you can't use it if it can already attack directly), and since it's a combat-related effect, it's terrible that you can't use it when going first