Has it been clearly defined what determines the end of one phase and the start of the next?
Example: Opponent has an artifact active with an ongoing ability (Lampstand, etc) and I discard it during prep phase. I want to play a card before battle but their artifact ability is stopping me (evil Dom, etc). Can I declare that I've ended my prep phase and am now in the battle phase where that ability is no longer active so I can play my card? or does the battle phase only start by putting a character into battle?