Helmed Horrors fight intelligently. They go after soft foes first and use thier magic to outmaneuver foes.
Helmed Horrors can move through the air, as the spell air walk. They can see unseen creatures and objects, as the spell see invisibility. They are immune to several spells. They can imbue a melee weapon they hold with a magical attack power.
The process of creating helmed horrors was something of a bad secret for many years. While unknown to the magical community at large, a great number of clerics of Bane, liches and evil wizards knew well how to create these constructs. It is now uncommon knowledge. A powerful spellcaster, with knowledge of both construct creation and arms and armor creation is needed, and a special workroom, along with the spells needed for the ritual.