Due mainly to wands of draining, drain resistance becomes a necessity in SLASH'EM's late game. The amulet of drain resistance is a very good choice for fulfilling this, at least for those who would otherwise wear an amulet of life saving or an amulet of flying. Be aware that a fast monster may be able to drain 2 (or possibly even more) levels from you before you can replace your amulet, resulting in a loss of level that cannot be immediately undone.