maimed_in_battle_effect

maimed_in_battle_effect = {
	random_list = {
		4 = {
			trigger = {
				NOT = {
					has_trait = one_legged
				}
			}
			add_trait_force_tooltip = one_legged
			increase_wounds_effect = { REASON = fight }
		}
		2 = {
			trigger = {
				NOT = {
					has_trait = disfigured
				}
			}
			add_trait_force_tooltip = disfigured
			increase_wounds_effect = { REASON = fight }
			epilepsy_brain_trauma_risk_effect = { CHANCE = 5 }
		}
		4 = {
			trigger = {
				NOT = {
					has_trait = one_eyed
				}
			}
			add_trait_force_tooltip = one_eyed
			increase_wounds_effect = { REASON = fight }
			epilepsy_brain_trauma_risk_effect = { CHANCE = 5 }
		}
		4 = {
			trigger = {
				NOT = {
					has_trait = maimed
				}
			}
			apply_maimed_trait_and_modifier_effect = yes
			epilepsy_brain_trauma_risk_effect = { CHANCE = 5 }
		}
	}
}

As written in game/common/scripted_effects/20_health_effects.txt.