The Spell of Revelation is an enchantment with which the true nature of one thing may be revealed. The Spell of Revelation - "Hierste þæt íecen sóna" - is powerful magic, but it applies only to objects, things, not to living creatures. Anyway, Merlin tried this spell on the troll Catrina to reveal her true form in front of the entire court of Camelot. Troll magic was so powerful that Catrina resisted to the spell, even though she felt it and had to take her potion again (Beauty and the Beast: Part Two). Merlin may have tired another type of this spell when he enchanted the vial containing water from The Lake of Avalon
Merlin tries to scry the Avalon vial.
that the Fisher King had given him. The sorcerer had told him that in Albion's time of need, it would have showed him the way. The young warlock tried to scry the vial and the first spell he tried ("Geriht læc me", which meant "True form, what is right for me") may have been a Spell of Revelation. Anyway, the only way to unleash the vial's power was to break it: this allowed Merlin to contact his deceased lover, Freya, the Lady of the Lake (The Coming of Arthur: Part Two).