Sympathetic Focus

This cantrip transforms a sample from any living creature (such as a bit of skin, blood, hair, saliva, or anything else that was once
part of that creature’s body) into a focus that can be used to target other spells.
   By using this focus when casting another spell against that specific creature, it decreases their saving throw by 5. This will
have no effect on area spells, nor will it work if the creature is on another plane of existence.
   The focus only remains potent for 24 hours, and is consumed when used, so it can only be used once.
The caster who uses the sympathetic focus need not be the one who created it.