mandala_war_victory_effects

mandala_war_victory_effects = {
	scope:attacker = {
		if = {
			limit = { has_realm_law_flag = piety_devotion_from_offensive_wars }
			add_piety = {
				value = medium_piety_value
				multiply = scope:defender.primary_title.tier
			}
		}
	}
	scope:defender = {
		if = {
			limit = { has_realm_law_flag = piety_devotion_from_defensive_wars }
			add_piety_experience = medium_piety_loss
		}
	}	
}

As written in game/common/scripted_effects/tgp_mandala_scripted_effects.txt.