Spell Thief

""Enough talk," Mugen said, whipping his book to the side. "I'm looking forward to your famous Crystal-Make. It will be a great addition to my collection."

The dust across the ground whipped up into the air as Mugen's grin grew wider. He was strong, Richard thought, truly dangerous.

"What's this about a collection?"

Suddenly, Mugen's eyes glowed crimson red. Richard's eyes widened as he felt himself step back off balance. His heart skipped a beat as a torrent of red enveloped the blazing trail towards him.

"Shit."

- The Hunter Becomes the Hunted in For A Friend

Spell Thief (呪文泥棒, Jumon Dorobō) is a holder-type magic, and as the name suggests, essentially allows the user to steal an opponent's spell and seal the aforementioned into a magically crafted book for later use after the needed conditions have been cleared.

Rules
However, aside from the need for the book to perform this magic, there are other limits to this magic. First, the user cannot steal Lost Magic, such as Dragon Slayer Magic, or magic of the highest grade, such as Fairy Law, which is sometimes referred to as uber magic. Next, the user can only steal magic that they have seen in use for more than five minutes and thus cannot automatically steal another's magic. Finally, after copying five spells, the user must wait for a time period of a month. It is important to note that when the user steals a spell, they do not actually steal it in the sense that the user no longer has access to that spell. Rather, the user copies and imprints this magic into their book. Spell Thief is derived from Mimicry Magic and is a weaker, holder-type variation thereof.

Trivia

 * This magic is very much inspired by Chrollo Lucifer's nen ability in Hunter x Hunter.
 * This magic was originally made for a now abandoned character.