Longcall Tonic

Thick, with a bright metallic smell, humming against the glass whenever the vial is set down on stone.

For one hour the drinker's ordinary speaking voice reaches every person they have named aloud within one mile, through stone, water, wind, and noise, and reaches nobody else at all. Shouting carries no further than a whisper, and the drinker hears no reply unless the answerer has also drunk.