The ancient Vulcan wedding rite, whose name means marriage or challenge, in which a bride may demand that her betrothed fight a champion of her choosing for her.
Koon-ut-kal-if-fee is the Vulcan ceremony that completes a bond arranged in childhood. It is held at a family's ancestral ground when the male enters pon farr. The bride may accept her mate or invoke the kal-if-fee, a challenge fought to the death by a champion she names, first with the lirpa and then with the ahn-woon.
The rite is seen in Amok Time, presided over by the matriarch T'Pau. T'Pring chooses the challenge and names James T. Kirk as her champion, reasoning that she will be free of Spock whoever wins. Leonard McCoy saves both men by faking Kirk's death with a neural paralyser.
Voyager revisits the custom in Blood Fever, in which Vorik claims the challenge and B'Elanna Torres elects to fight him herself. A dream version opens the Strange New Worlds episode Spock Amok.