Scripts

Is there a way to start a battle on a specific arena without using StartCombat?

Through SiegeTown(hero, city, arena).

Added 8 minutes later
The second option is to use the console command arena_override, which forces the game to conduct all non-siege battles exclusively on the specified arena.
To enable:

consoleCmd('arena_override path_to_arena')

To return to normal arenas, which depend on the type of terrain:

consoleCmd('arena_override 0')