Not done yet

With the defeat of the spell weaver, the Headmaster was freed from his herculean effort combating it. He unsteadily rose and expressed his deep appreciation to the party and says there is one more thing that must be addressed immediately.

Attempting to take a few steps, he faltered and almost collapsed from pure exhaustion. Turning to the heroes, he handed them a small crystal he had retrieved from the spell weaver. "Please take this and go to Founders Hall. This crystal will guild you to a door in the basement and will unlock it. Descend the stairs and tell the creature that is living there it is free."

Heading for the Hall, the party found the stairs, and descended them. They ended is a tunnel that ran for several hundred feet. The party suspected they were outside the walls of the academy. At the end of the tunnel was a large door. There were 2 shelves on it. On the top one were 9 crystals. On the bottom one were 4 bins.

There was an inscription in the door.
Sort the crystals into the bins, but never pair them together,
Only through oddity, will the door be opened.

Seeing that it was 1AM and I wanted us to finish, I told the gang what they needed to do to solve the puzzle, put the 9 crystals in the 4 bins, but always have an odd number of crystals in each bin.

I think Jeff got it in less than 5 minutes, stack the bins inside each other.

Opening the door revealed an enormous beast. It was horribly scarred and appeared to be near death, probably from old age. As they stared at it, it becomes aware of them and awakened. As it moved it’s head to see them, they realized it was a dragon. The glistening of the party's sunrod off it’s body indicated something they hadn’t seen before…it was silver.

“I’m so tired. What can I do for you?”

“Thank you. Now please stand back in the hallway while I collapse the ceiling so I may leave.”

As he climbed out of the lair, he turned to it's liberators and asked “Do you know of any of my brethren that are still here?”

Alexander stepped up and told him the tale of the egg stolen by the Sahuagin.