Comments posted to our Dark Souls 3 Wiki
Lycanthropes drop these about every other time.
Where are these Lycanthropes at, been a bit since I played
Sources of farming
Offline users: Lothric Knights (early & late game)

Online users: Invade!
I swear to God it must be hard-coded for enemies to rush you when you're using these things.
QnQ my friend thinks having this = higher stats
Well he's not wrong, unless he thinks it's stuff like Attributes
"Ugh, all these darn invaders ruining my pve experience! Lets ignore the fact that I'm the one who used an ember, summoned in all my friends and maybe even use a dried finger to summon more friends, all of which are things that greatly increase my chances of being invaded! All i want is uninterpreted co op with my friends! I mean what other game could I POSSIBLY play that allows me to do that?!?!?!?"
set a network password
Git Gud.
This explains the Invader I saw when I was playing yesterday. I thought it was an NPC invader (as I know those happen) but I noticed the... title, I think beneath the Invader's name that looked a LOT like your common Guild name in an MMO. I think it was something like "Champions of Spug" or something like that. I remembered that I had set my experience to "offline," but had used an Ember just before being invaded to get my HP back.

Lesson learned, I'd say.
Can someone correct "Able to summon other players via soul sign" to "White Sign Soapstone"