More ideas that I've been mulling over:
An "Altar of the Moon", outside-only, consumes totems and souls to craft a "Dark Wyrd"- a sort of "weapon" that detonates on a successful attack, degrading itself into nonexistence and releasing a cloud of horrible syndromes. (Possible?) Give it to an undead squad and you get suicide bombers, stick it in a weapon trap and you get a landmine.
Make souls brewable into "Living Spirits", a drink that staves off hunger and sleep as well as thirst- but with a large penalty to movement speed.
"Cerberic Hounds", an opposed to life dog with three heads. Vicious warbeasts and impressive pets, plus their multiple heads mean that you can efficiently farm totems from them.
"Elysian Shades", fuse 4 souls together at the "Altar of the Moon" to create a shade. Shades don't do anything but wallow in self-pity, but can be "sheared" for a soul once a season when invaders are scarce.
"Thralls", an odd species that loosely resembles a spider crossed with a bat; warlocks originally created them by accident, but continue to raise them for their high tissue yields. Thralls can be made at the Augmentation Lab at a moderate cost or slowly bred in captivity. Comes in 4 unique castes: 60% of being a "Flesh Thrall", a pathetically weak monster consisting largely of vestigial smooth-muscles and stunted appendages. 15% of a "Bone Thrall", these varieties have so much bone-mass that they can barely move. 15% of a "Skin Thrall", a mature specimen often has enough skin to cover a horse- though the creature's actual size is closer to that of a rabbit. 10% of a "Brain Thrall", a horrifyingly fast beast composed mostly of nervous tissues, that paralyzes its prey with a jarring pain attack before ripping into them with its deadly claws and fangs. May attack even a long-time handler without warning.
"Ratkings", a group of 6 head-sized rats fused together. Breeds quickly and often picks fights over crowding; contact with their claws causes an eruption of blisters and boils, while their bites can cause necrosis and mild paralysis. Good for guarding secret entrances with.