This creature can be found at Tul's Breachstone

How to create Spectre bank and what for you would need it

Sometimes your Spectres may die so you have to raise new ones
Everytime you use Desecrate - you refresh the list of creatures which would be spawned
(each map contains list of creatures, might include additional conqueror packs if the map is under influence)
For permanent access to chosen spectre corpses you should do next things :

Move to map with desired creatures
Use Desecrate to spawn corpses
(Hold 'A' , mouse over the corpses and use Raise Spectre when you find desired corpse
Remove Spell Echo if its equipped to prevent double cast)
Move to hideout and use Desecrate
Switch back to Witch u have just created
Use desecrate and quit

Create new character > Choose 'PvP only' to get level 28 character, which
is the minimum for Raise Spectre and logs directly into your hideout
Reset all passives and path to Death Attunement including str/dex nodes
Take Desecrate and Raise Spectre from stash tab and insert them into any sockets
Switch to main character

Use your main character to buy Desecrate and Raise Spectre ( Lilly Roth, A6 )
(Gems must be of the first level)
Move them to stash tab

Now your PvP-only Witch has fixed list of creatures spawned by desecrate
Once you need to respawn died spectres - Turn to 'Pvp-only' Witch > use desecrate >>> switch to main character, move to hideout and press desecrate to gain desired corpses

What Spectres we will be using :
Move to Ashen Fields (Act7) and summon
2 x Carnage Chieftain for Frenzy Charge generation
and 1 x Host Chieftain for Power Charge generation
(Use Desecrate, Hold 'A' , and select the correct corpse)

If you farm Blight maps/Simulacrum you can use They of Tul spectre
It casts snowstorm which protects you
You take less damage and have a chance to dodge while in it