Chapter 640: Steadily

 Ryan confirmed that the palace was nearly defenseless as they approached, thanks to Clairvoyance. In the end, Ryan didn't know if it was due to Poseidon's carelessness, Isis's plan, or due to the fact that Hydras had to fight each other in order to make the dungeon level up faster, either way, the storm that once worked as a defensive barrier for the dungeon was no longer there.

"Now!" Ryan said and then teleported Gustavo's group to underwater and right above Poseidon's castle.

 While Ryan couldn't go that deep in the ocean, the castle was within his range as a human. Regardless, after that, Gustavo and the others used Draconic Transformation and began to attack the massive walls around the castle. However, despite that, it looked like they were just a few ants scratching an elephant. While it wasn't tall, the castle makes up for it with its lengthiness. 

"I can't sense your dragon's presence," Gustavo said via telepathic link.