Heroes of Might and Magic III: In the Wake of Gods is a massive modification of HMMIII inventing script language and generally intended to stretch the boundaries of the original game capabilities. HMMIII WoG presents new objects with various properties, drastically changed and improved creature abilities and a wide variety of custom scripts for altering the gameplay.
A random gameplay video made by Oscar.
Youtube.com
On this video you can see some new creatures including Nightmares, black horses familiar to us from Heroes of Might and Magic IV.