Things such as being judged 'dead' referred to any movements or actions that the enemy would give to the victim which was seen as a fatal move.
This kind of way to declare the winner was rare because usually, the fighters would fight with tons of small injuries and wait until the judges said that one of the fighters could not possibly continue the battle.
On the other hand, the 'fatal move' was just like when someone put a knife on someone else's throat.
Even if there was a chance that the targeted victim could dodge the threat or something, it was already considered a fatal move by the judges in this battle arena.
The Dryad girl felt that the little boy wanted to use a 'fatal move' rule to knock her out of her game, not wanting to drag the time to fifteen minutes so that when the battle ended and there was no winner yet, the boy automatically won.
