Blue-Bearded Noble

Reveal {2}{b} (At any time, any opponent may pay Blue-Bearded Noble's reveal cost. If they do, sacrifice a creature and reveal Blue-Bearded Noble. While revealed, Blue-Bearded Noble is a 4/2 blue and black monster noble with menace.)
All the inhabitants of the town dismissed the woman's statements of the noble killing her sister as grief. Then the knight of the rose arrived in the town and revealed the truth...