Knuckle Bine

Knuckle Bine
An Unidentified Beast Hunter and Morel's apprentice. Despite appearing to be an aggressive man, Knuckle is very compassionate and easily moved to tears. Knuckle also gets along well with animals, having the habit of taking care of abandoned pets. He competes with Gon to decide who's going to the Chimera Ants mission, teaching him along the way but ultimately defeating him.

Castle Raid Arc
He participates in the castle raid to stop the Chimera ants

Nen
Knuckle's ability is "Hakoware: Bankruptcy, Chapter Seven." It involves conjuring an indestructible mascot called the "Amortizing Power Redirector (A.P.R.)" ("Potclean" in the Japanese manga) onto the opponent after being dealt a blow from Knuckle. A.P.R. constantly lends Knuckle's aura to whomever its attached to, displayed by a rising counter on its forehead. As long as the A.P.R. is attached, any attacks done to Knuckle by his opponent return aura to him, lowering the counter. Until all of the aura lent by Knuckle is returned to him, Knuckle cannot be physically damaged by his opponent. The reverse is also true—each of Knuckle's blows only lends aura to his opponent, causing no damage (though in both cases the one receiving the blow may be knocked back by it). The interest rate on A.P.R. is 10% of borrowed aura, accrued every ten seconds. As the amount of interest accumulates, A.P.R. also grows in size. If the aura borrowed from Knuckle exceeds his opponent's total aura, the opponent goes bankrupt. Bankruptcy causes the conjured A.P.R. to transform into the "Individual Ren Suppressor (I.R.S.)" ("Toritaten" in the Japanese manga), a demon-like mascot that follows the debtor for 30 days and forces them into Zetsu. The victim only accumulates interest when within 100 meters of Knuckle, but Knuckle can track the general location of the victim at all times, no matter how far away they are.
 * Nen Ability: Hakoware (ハコワレ 「天上不知唯我独損」), lit. "Breaking the bank"