Know Alignment (Divination) Reversible
Range: 10' or within the same zone as the cleric.
Duration: The rest of the scene
Components: V, S
Area of Effect: One Creature per action (at a time)
Casting Time: 1 action
Opposed By: n/a (but can be countered, see "Reversible")
A Know Alignment spell enables the cleric to exactly read the aura of a person - human, semi-human, or non-human. This will reveal the exact alignment of the person. Up to 10 persons can be examined with this spell.
Any Alignment aspects which are present on the creature touched, are now known to the cleric. The exact nature of the aspect is revealed to the cleric.
There is no variability in this spell, so no die roll is needed under normal circumstances.
"Declaring a Story Detail"
If the player expends a Fate point during the casting, the player can declare a story detail about the cleric character detecting a target's Alignment. The nature of the aspect would be up to the GM and player to justify any details about that aspect. (Fate Core, p. 13).
Reversible (Obscure Alignment)
The effect of this is to MODIFY an existing "Alignment" aspect that already upon the target to make that aspect "hidden". Unlike the normal version of this spell, this can only be used on a single charmed creature.
Note that in the case of Alignment in Spirit of Greyhawk, not all creatures have an Alignment. So this reversed effect will give the cleric a (false) result of having no Alignment or Unaligned. Fans of the source material should bear in mind that an Alignment of True Neutral is normally not the considered the same as having no Alignment.