From Ardrana

The sunscorch spell creates a brilliant ray of scorching heat that slants down from the sky to strike one target of the caster’s choice. Any creature struck by the ray sustains damage, with undead creatures and monsters vulnerable to bright light being particularly susceptible. In addition to sustaining damage, living victims are also blinded a few minutes.

The sun must be in the sky when sunscorch is cast, or the spell fails entirely. It cannot be cast underground, indoors, or in hours of darkness, although routine overcasts do not hinder the sunscorch.

Note: Sunscorch originally appeared in this form in the Player's Option: Spells and Magic supplement for the AD&D game from TSR. Their use here is for the purposes of providing context for the campaign only.