In Magic the Gathering: Puzzle Quest, what does the Objective "Defenseless: Summon no creatures with 0 during a single fight" mean? I've apparently achieved it on at least one battle, but I have no idea how. The grammar doesn't really make sense.
It means that you did not "hold" a creature to summon and instead summoned it immediately when you could so if you had a creature that needed 3 mana and you matched 4 and you had either "grayed out" the summon or there were already 3 creatures on your side you decided not to summon the creature that turn.
That creature when summoned will be considered "summoned for zero"