Can a Magic Circle be concealed and used as a trap?

Question

The description of the Magic Circle spell states that 'glowing runes appear on any surface the cylinder touches'. This makes it difficult to use as a trap. Obviously if it is cast in a room, runes will appear on the roof and floor. However, if it is cast on the ground and then covered with leaves, will runes appear on the leaves? If an illusion is cast over it, will glowing runes appear on the 'surface' of the illusion? What about using a glyph of warding?

Is it possible to conceal a Magic Circle so that it cannot be seen? How can Magic Circle be used as a trap?

Answer 1

Yes, it is possible to conceal a Magic Circle. You cannot do it with physical objects because in order to cover the runes that appear at intersection points you have to have those objects intersect the cylinder.

It can be done via magic. The spell Darkness creates a 15' radius sphere of darkness. Choose a point 10' off the ground in the center of the Magic Circle cylinder and the whole area will not be seen.

Most illusion spells (eg Silent Image, Hallucinatory Terrain, Major Image) can also create visual effects that hide the glowing runes.

Glyph of Warding can be used to store a Magic Circle until the triggering conditions are met, allowing the Magic Circle to be used as a trap.

Answer 2

If you are trying to use a Magic Circle as a trap, perhaps attaching it to a Contingency spell so that when specified conditions are met the Magic Circle is cast. This will avoid having to do anything to tamper with the appearance, minimizing chances of detection.