Pentacle Enchantment

"Even if it is possible, we have no way of knowing for sure. Or do we?"

- Gaius to Merlin about whether Lancelot is a Shade

Pentacle Enchantment are enchantments used to determine whether someone is a Shade.

History
Merlin used a pentacle enchantment to determine whether Lancelot was a Shade. Following instructions from The Art Of Necromancy, he drew a pentacle on the floor of Gaius's chambers with silver paint. It appeared to be a spiraling circle with eight dots spaced evenly around the edge.

When he finished drawing it, Merlin placed an enchantment on the pentacle, then hid in a nearby cupboard with Gaius. When Lancelot later walked across the pentacle, it emitted a ghostly wail and his face briefly appeared as a skeleton, thus confirming that he was a Shade.

Trivia

 * When Merlin enchanted the pentacle, it briefly glowed as if heated (Lancelot du Lac).
 * Whether this enchantment works on all undead creatures or just Shades is unknown.
 * The pentacle Merlin created was similar in appearance to the emblem on the magical coin Morgana used to summon Lancelot from the dead (Lancelot du Lac).