[Third Person POV],
Ace had observed a habit from the dragon phantom.
He observed that the dragon always roars when it is hurt or about to strike. Although this habit of the dragon phantom appeared to be quite normal and was in fact normal, Ace had an idea because of it.
For one, Ace was the only person in the group who was still unranked, so his attacks were unexceptional and carried no real damage that could reasonably injure the dragon phantom. In addition, he was unable to engage the dragon phantom in close combat.
Ace had no confidence in even penetrating the dragon phantom's shell, despite the fact that it was not any weaker than when it first materialised.
Ace was certain that approaching the dragon phantom at any moment would be a suicide attempt. The risk involved in accepting this risk was simply too great.