Lucretia's plan was for Asher to sneak into Illithyia's room and substitute the abortive concoction with bitter water. Afterward, Lucretia would deceive Illithyia into thinking that her pregnancy was destined to occur, effectively thwarting her plans to remarry—presumably without Glaber ever learning of the ordeal. Instead, Asher capitalized on the situation and told Glaber about Illithyia's medicine, ensuring that Glaber would still believe him useful (and not execute him). Illithyia could have covered the while thing up with Glaber confronted her, but she obviously felt confident that nothing would go awry at the arena.