Editing Horn of the Abyss (Documentation) (section)

===Gameplay===

* The first day on an arena map is a preparation day. On this day, players visit objects on the map, get or hire an army and prepare their heroes for battle.
* Heroes have unlimited movement points, and players can construct any number of buildings in any town. For certain objects, information about their contents is displayed in the arena mode.
* A correct arena map must be designed so that players cannot meet on the first day. If HoMM3 HD-Mod is installed, it is recommended to use simultaneous turns until the first day. At the beginning of the second day, the combat starts automatically.
* One or more combat places must be set up on an arena map. A combat place is made up of the main square (on which a hero can stand) and an attack square (from which the attack will be launched). During the first day, the attack square is blocked by an obstacle.
* It is assumed that one of the players can order a hero to stand on the main square (and thus select the combat place), and then the other player’s hero will be teleported to the attack square (the obstacle will be removed from it beforehand) and will attack. If a player’s hero does not enter any combat place, he/she will be teleported to a random place. There may also be other ways to use combat places.
* After the combat, the winning player automatically wins the game.