Butcher's Eye fires every so many crits. On Kindled Heartspike Relic it reads: Every 5th critical strike opens a bleeding wound for 60% of the hit.

Word for word it is Every {count}th critical strike opens a bleeding wound for {value}% of the hit, and the number in it grows with the gear: 60 to start, 4 more for every item level, and it only goes off every 5 times you set it up.

It leaves Bleed behind, which makes it Blood build material.

3 bases carry it.