alchemy

錬金術、変形させる力 ◇Ar.al(＝定冠詞)＋kimiya

(noun) A medieval chemical philosophy having as its asserted aims the transmutation of base metals into gold, the discovery of the panacea, and the preparation of the elixir of longevity.
(noun) A seemingly magical power or process of transmuting: "He wondered by what alchemy it was changed, so that what sickened him one hour, maddened him with hunger the next” ( Marjorie K. Rawlings).

Once the alchemy is there, a writer can usually work swiftly and efficiently, avoiding many writing pitfalls and completing the book in less time than (s) he expected it to take.