SLASH'EM introduces two new properties derived from D&D, the Need +x weapon to hit and Hits monsters as a +x weapon, where x is an integer from 1 to 4. Essentially, monsters with the first property cannot be damaged with weapons with less than the required enchantment. It is effectively enchantment resistance. The second property is mainly of relevance to those who keep pets, in particular, pacifists, as an otherwise strong pet may be unable to damage a particular monster. Note that these two properties are given to both new monsters and monsters from vanilla. It is possible to gain the Hits monsters as a +x weapon property through polymorph, but not the Need +x weapon to hit property.