The original host (version 3.20 and later) provides three places where add-ons can hook in. These places are usually called "auxhost":
- Auxhost1 is run directly after processing the turns.
- Auxbc is run between movement and combat.
- Auxhost2 is run after host processing, before making the results.
In addition, there's a fourth hook (auxbatt) which allows replacing the combat with something different.
Compare PControl.