/he-vē wi-zər-drē/
n. Code or designs that trade on a particularly intimate knowledge or experience of a particular operating system or language or complex application interface. Distinguished from deep magic, which trades more on arcane *theoretical* knowledge. Writing device drivers is heavy wizardry; so is interfacing to X (sense 2) without a toolkit. Esp. found in comments similar to "Heavy wizardry begins here...".
Compare voodoo programming.