I once read a book about a group of people who discovered a hidden temple city in a mountain range, where the Incas-the ancient civilisation of Peru- had fled to when the spanish invaded. When this group found the burial chamber of one of the inca high priests, they unleashed a powerful curse upon them all...
During battle/war the heads of all slain are decapitated and collected by the slayer. The slayer will clean them up and put them on display for inspection by the commander. Depending on the deads name, rank, and expression on the face held by the death blow-the slayer will be rewarded by gold and/or status.