Extended Uppercut
An extended uppercut, or "extended", is a movement technique that extends the distance of a conventional punch uppercut spin. Spacing out the inputs of a punch uppercut spin leads to more air time, thus increasing the vertical and horizontal distance. Unlike a boosted uppercut, Jak's direction can be altered during the duration of an extended uppercut. Additionally, the starting jump height is restored after the spin input.
Extended uppercuts can be performed in Jak and Daxter: The Precursor Legacy, Jak II: Renegade, and Jak 3.
Dark Jak
In Jak II: Renegade and Jak 3, a special variant of the extended uppercut is possible using Dark Jak's triple punch. As with the standard extended uppercut, the Dark Jak extended, or Ichorcut, restores height upon the spin attack, allowing this variant to cross much greater distances and also pass underneath obstacles.
Discovery
It is not currently known how or by whom the original extended uppercut was discovered. The Dark Jak variant was discovered by Av_Ichor.