I keep thinking it would be amazing if the game had an "Arena Mode" in the main menu just for battles between characters. Whether against friends online or with characters created by yourself and having them fight in turns. Or one party against another. Or even pitting monsters from the game against your own character. It would be perfect!
I don't know if it has been kept up to date by the author with the current version of the game but there is a mod called " Trials of Tav " that kinda works like the game in arena mode, you may want to look it up.