It is not exactly a MUDRA , but here it is. Go out and stand on the ground, rub the sole of your right feet(bared) on the ground, take dust from that part of the ground and hold it with the tip of your five fingers. Then bring it near your mouth and blow it upwards. You have to blow it in such a say that it goes up and then falls on your head. This is the most critical part. Practice few times and it will happen effortlessly.
Got it from a siddha level yogi who mostly spends time in the Himalayas meditating. But yes, there are siddhas living over 1800 years, like babaji, may be even master sunam. He is probably most junior siddha, attained his state within few decades ago. Not all are of same stature. Tried to be accepted as his discipline but it turns out he is not interested.
He said that, the right part of the body corresponds to the divine and the left part to the astral.( in a relative sense) And we live in the realm of EARTH (where solitary is most essential for life) , the physical world. So using earth and the right side of the body one is basically stopping the attack from manifesting in OUR world. He also said doesn’t matter how powerful the attack, or the attacker is THIS WILL WORK TO STOP IT.
Hope it helps.