After the impact from [Heaven's Spear], the entirety of Termina, which means the trial, was destroyed, including the [Hollow Tower].
Even he didn't expect it to be this powerful, but it also means that if he had decided to use it since the beginning, this entire trial would have been over in seconds.
If he did that though, Sora and Lilith would have died, even though he wouldn't have known of the latter anyway.
The [Hollow Tower Square], being the main point of impact, received the highest percentage of destruction, a massive crater appearing in the middle where the participants previously were.
Stark, on the other hand, completely disintegrated because he had simply just tanked the projectile without even defending himself.
Well, even someone that was kilometers away from the square would have still died, but Stark still took the entirety of the impact.
All he could see now was black.
"Here again, huh."