Oh, sorry...let me clarify!
I was just wondering if it was common to cast a circle of protection for ANY kinds of divination. Rune casting, tarot reading, crystal ball gazing, mirror scrying, etc.
Oh, it depends on the type of divination you are using. Pendulums faily safe, you can charge them or just cleanse, dedicate it. I never have to cast a circle for readings.
But if you have a pendulum chart, a once only charging with that chart is simple. In your circle after saying a chant (one for charging it) 3 times, pick up the pendulum and ask questions over the chart. Now put down the pendulum and finish building up the energy in the circle.
A crystal ball...a good psychic powers ritual first 1-3 times doing a reading (or until you don't need it). I never tried charging a crystal ball, but it becomes charged by using it a couple times, during a good candle burning ritual.
Mirror scrying, I've always used a circle, unless it is charged with a good psychic powers spell.
To use a mirror you have not charged with a spell...
Cast your circle, say this chant 3 times.
â€œMirror, mirror, (or crystal ball) let me see;
Goddess show the truth to me,
Goddess light, mirror (crystal ball) now so bright.
Past, present, future, all shall soon be clear;
Out from darkness shines my hope,
No more to fear the secret things hidden.
Mirror, mirror, (crystal ball) scry for me,
As I will so mote it be!â€
Runes, just need to become in tune with them...possibly a water element spell of the West.