the Dark Moon has its core working in banishing, transformational or journey work, cuttings and introspective contemplation. The Full Moon and the Dark Moon are both excellent times for scrying in your black mirror, in the embers of the fire, or using whichever form of divination that you see fit.
The blackthorn tree is one of the eight chieftain trees in the Ogham divination and it is the great protector. Burning it banishes any negativity. If the attack is intense, burn blackthorn for a period of seven days on the waning moon and you will be cleared of all curses or ill intent.