It allows an illusion of the caster to be projected over far distances. A very useful spell, but there must be a mage on the "other side" who can receive the vision, or a special area where a necessary ritual has been performed. Once connection is established, the caster and the recipient can converse normally, just as if they were standing next to each other. The spell is normally used to communicate between Sorcerer's Guilds, but in some places, ordinary people are also allowed to use it for a price.
In an interview in one of the guidebooks for the Slayers TRY anime, series director Takashi Watanabe raised the possibility that Amelia gave her bracelet to Zelgadiss at the end of the story so they could communicate with each other using the Vision spell.
(Article taken from Slayers Universe.)
- ↑ Encyclopedia Slayers, pag. 220