If you control a "Libromancer" monster: You can target 1 face-up monster your opponent controls; this turn, that face-up monster cannot be used as material for a Fusion, Synchro, Xyz, or Link Summon. You can only use this effect of "Libromancer Prevented" once per turn. Once per turn, during the End Phase, if you control no "Libromancer" Ritual Monsters: Send this card to the GY.