Related Rule
Practice Relating to Rule 65. Perfidy
Section C. Simulation of being disabled by injuries or sickness
Belgium’s Law of War Manual (1983) states that “feigning being wounded and wanting to surrender and firing at an adversary willing to help” and “showing signs of distress in order to mislead the enemy” are acts of perfidy. 
Belgium, Droit Pénal et Disciplinaire Militaire et Droit de la Guerre, Deuxième Partie, Droit de la Guerre, Ecole Royale Militaire, par J. Maes, Chargé de cours, Avocat-général près la Cour Militaire, D/1983/1187/029, 1983, p. 32.
Belgium’s Teaching Manual for Officers (1994) prohibits perfidy. For example, “feigning being dead to avoid capture is lawful, but not feigning to be wounded to kill an enemy who tries to help you”. 
Belgium, Droit de la Guerre, Manuel d’Instruction pour Officiers, Etat-Major Général, Division Opérations, 1994, Part I, Title II, p. 33.