Hunter's Reliquary

A masterpiece of some ancient eldritch smith, this
magical receptacle is made for carrying a small
amount of blood. While attuned to this item, you
can sense the precise location of the creature
whose blood is stored within, and any attacks you
make against them are considered a critical hit on
a natural roll of 18-20. Additionally, you may use
the reliquary’s magic to cast the hold monster
spell against them once per long rest
(spell save DC 15).