Simon had to act like an assassin to safely reach the northern tower.
He had to hide behind walls, hide in partially ruined buildings, look for dark spaces to move, and also avoid any Bulwark demon since they would just waste his time.
One thing Simon realized was that there were very few shadows in the stronghold where assassins could hide.
Usually, in a city like this, shadows would be everywhere and the assassins of the Shadowgrave Clan would be able to hide in the shadows and kill their enemies before they even knew it.
However, Simon came to realize that places that should normally have shadows, would be absent of shadows.
Some places had unknown sources of light, preventing the formation of shadow, and some places with a shadow or shadows were just too exposed.
Some were even engulfed with flames, but these flames did not spread and burn even with the chaos happening all around.
