The bases are thick plasticard. Using liberal amounts of hot glue, I attached beads, old miniatures, giant rib bones, bits and piecs to the bases. Then I gave them a thick spray of gloss black paint.
A large pit of seething black sludge bulges as if about to give birth. Then a shape breaks the surface and slowly rises. Forked prongs first appear, then a long blade ascends. None of the pitch sticks to it. The edges of the otherwordly sword glitter. Glowing blood-red runes hurt your eyes. The weapon is easily twice the height of a tall man. No hand holds it aloft. The blade's grip emits a constant flow of hot, black pitch.
"Hello," she says in a maternal voice. "I am Fathom, Demonlord of the Devouring Pit. Free me and free yourself!"