Involving communication with the dead, often for magical purposes.
Necromantic things are often thought of as scary or mysterious.
Examples:
She practiced necromantic rituals in the old cemetery.
The necromantic spell summoned the spirit of a long-dead king.
The necromantic book was full of strange symbols and words.
The necromantic potion glowed in the dark.
The necromantic power could raise the dead.
The necromantic ritual was performed under the light of the full moon.