This is one of the powerful Wyld Rites practiced by followers of the wyld faith(s).
The Ritual of the Worms of Memory causes an area or person to have their memories eaten away. They become faint, and cloudy. It is the power of Mog Creoch to take the weave of the pattern and unravel it. The tears are small, and can easily be mended, but can be used to nefarious ends.
This is sometimes confused with Exhumed Memories.
The ritual is said to often be used to provide a calming influence for sacrifices to the unending hunger of The Devourer, Mog Creoch.
Although the ritual can be used to wreak havoc on personal memories, those powerful enough are said to be able to target places, events, and knowledge – to literally cut it from the memories and thoughts of all who have recollection. Such things are said to require horrific sacrifices, and expose the caster to the notice of the denizens of the Feywild.