Can an action be readied with the trigger for the action being "when the duel begins"?
For example, I want to cast a spell, or charge, or fire an arrow, as soon as the duel begins, but before anyone takes their turn. The reason I am bringing this up is because the GM is saying that you cannot ready an action out of combat, and is saying that as such, I cannot prepare an action right before the start of a duel.
I can't find any rules that say I am unable to do this, but he remains adamant that I need a surprise action to be able to do this. I want to be sure I am not missing anything in the rules about this. Am I?