When exactly does the opponent have to deal damage? After a complete squad of attackers is declared, or once this guy has entered the fray?

I would agree, and suggest that all effects not be used between 1st engaged unit declared and last- you could get into some sticky "I react to that unit being added, I declare this unit with shielding, etc" Aside- a better ruling on how keyword fit into timing would be nice- mainly shielding (seems like it would function like a reaction) and protect (interrupt) -I think it would be best to keep the "like a" anything else is a whole new worm can