Where to acquire vampire talismans?

Self explanatory. Looking to use the vamp+warlord combo.

One of the Brave New World dungeons I think ? The mage/assassin blue/purple one. I forget the name of it offhand.

Yes, Garden of Dismay is where you find the vampire talisman

Speaking of Vampire talis, there are two different descriptions. The one on home team screen and the one in game.
One says heals 20% each turn, the other says only on perfect hits..... something like that.
I've never seen them work. Rarely see them in Arena.
Which is the accurate description?

They heal 20% on perfect hits... so it's a combination of both.

They WERE broken for a while and healed the ENTIRE TEAM... but, they fixed that recently. Now they only heal the character wearing them like they were supposed to. They do indeed work. I use then on Eternity Ed and the Witchdoctor.

Is there any advantage of using Vampiric Set over Sustaining, Greed, Hex, Angel or Oracle?

I would imagine with characters/allies that provide perfect hit status, they would be great. They had a 2 tali set recently in the store that provided perfect hit. Pairing them with those would help.
Advantage talis offer 50% chance for perfect hit status on perfect hits.
If one didn't have Greed/Warlords, then Vampiric would be a substitute on KP who gets Perf. Hit status.
Still, I think the ones Olevipoeg mentioned are better, but Vampiric would also be good on a toon with low HP, like Beast w/ 666 Hp.