This spell takes all night to cast, and the caster must sleep after casting it for it to take effect. While they are casting the spell, the night, from horizon to horizon, reports on everything that it sees. It delivers this report to the caster in a dream when next they sleep. If they do not sleep before the next dusk, then the report is lost since it will be an entirely new night.
The longer the caster dreams, the more complete the report will be.