AzzyAI is a powerful and flexible AI for use with the Mercenary and Homunculus systems in Ragnarok Online. It supports both interactive leveling with the homunculus or mercenary and AFK leveling. It supports autocasting of most any skill that you would want to trust an AI to cast automatically for you, including appropriate use of AoE attack skills and automatic casting of buff skills. The most recent releases support all mercenaries and homunculi available on iRO as of March 2012. I am happy to say that AzzyAI has been the most used mercenary and homunculus AI on iRO for years.
AzzyAI has a huge selection of options, allowing customization of homunculus (or mercenary) behavior to suit almost any forseeable circumstance. Whether you just want to AFK level, need a passive buffslave (for example, with painkiller, overed boost, or magnificat), or want to level alongside your companion, AzzyAI can handle it! Configuration is handled via an easy to use configuration tool (full support only available with 1.50 and later)