Chill looks up at the tower.   

"Yes,  I could climb that easily enough.  Wouldn't be the first I've snuck into.  But what are we even looking for?   Keys you say, or something else?"

He continues to ponder the tower for a moment. 

"I'll climb up there if you want me to but I don't know what to look for.   Might be best we had in together."

(If there is a door, Kazri will check if it is unlocked.)

Xerophon looks over at Rhogar,

"No,  I'm just a servant.  The power of magic was never anything that I had any aptitude towards."

Looking up at the tower to see that the stones that were used to build it are still in good shape, the only damage seems to be the roof.  Working your way around the tower you find the entrance.  The door is rotted wood and nearly fallen apart.  It isn't locked, the door barely hangs on its old hinges.

"Ahh, right! You've mentioned as much as before I believe, or at least something along those lines. Seems my nerves are a bit more, uhm, frayed than initially, eh, believed." Rhogar gives Xerophon his best apologetic grin, if though a touch intimidating. As he's turning to address the others, seeing Kazri begin to circle the building in search of another entryway forestalls any thought to do such in favor of following along after her and motioning for the others to do much the same. 

"Hmm... Seems I misjudged things a tid bit. Or maybe -- no. No more of that. If a more adventurous path is to be reconsider-" He shoot Chill and Krom each a look in turn. "-let's see if we can finish what time and the crash has done to the doors and find our way inside." Rhogar cracks his knuckles, ready to pry or at least help in removing the door. 

"Let me help you with that door Rhogar." Krom nods to the dragonborn and uses one of his axes to hack away the rotten door. "Do you think that those Drow and the red tiefling are in the city at the moment?" asks the dwarf "We haven't seen any signs of them or any other living person, beside our friend Xerophon, but they could be too trying to reach the Mythallar."

Perception: 21

Kazri checks first if removing the door will cause any further structural damage to the building. If not, she will carefully remove the door with Rhogar's help.

Athletics: 28

You are able to easily pry the wood that remains apart and pull the doors open.  There is no fear that any further damage will happen to the building.

Entering you find an open room, 30 feet in diameter.  The remains of furniture and rugs litter the floor. Everything is smashed, broken, or decayed to the point that it is unusable.  A single set of stair loop around the outer wall up to an opening to a floor above.

Making your way up the stone stairs you climb to what appears to be the top level. 

Large gashes in the roof allow you to see the dark, icicle-festooned roof of the great ice cavern beyond.

Silver light emanates from a three-foot-diameter glass orb situated atop a two-foot-high cylindrical stone plinth in the center of a thirty-foot-diameter, rubble-strewn circular chamber. Eyeballs drift inside the orb, like fish in a bowl. Some have cataracts, while others are bloodshot or pus-filled, but all turn and gaze at you as you approach.

On one of the walls an inscription in Draconic reads: “Third, a burnt palm loosens the tongue. Sh"  The wall is broken off and it appears there would be more words but a chunk of wall is missing.

"I wouldn't put pass them." Rhogar replied while working on the door alongside the others. "But if they are, then they aughta be just as stymied as we are with finding the 'keys' to unlock the way. And if that's the case, could be when we do meet, they might spare us the effort of searching ALL the towers for answers we seek. Though just how willing they'll be to part with it all..." The dragonborn trails off from there offhandedly waving a hand in dismissal.

The way was open, and there would be plenty enough time later to speculate. "Third, a burnt palm loosens the tongue?" Rhogar would later find himself translating for the group. "There's a bit more after -- mere letters really to the start something else. But, I dare not even speculate. We check outside again to see if the missing piece is elsewhere nearby. Though I fear that for -that- piece, we may need to consider other alternatives." He say sto teh group. 

"I guess we'll see how they react, if we ever meet them." says Krom as the groups enters into the tower. 

"What are those things? Undead or arcane constructs?" the dwarf points at glass orb with his hammer when he reaches the circular room.

"A burnt palm loosens the tongue? That sounds more like something you would find in a torture chamber than a wizard's tower, but considering how Xerophon was treated by his master, it might be the same thing for the old Netherese."

The dwarf takes out from his backpack the Professor Orb and then helps searching the room for fragments of the missing wall.

Slight edit - last line should be

The wall is broken off and it appears there would be more words but a chunk of wall is missing.

Krom - make a religion check 

You search the room but do not find any blocks that have the missing words.   Any additional searches around the exterior of the tower also do not reveal anything of any value.

"Well, what do you think it is Krom?  This is the Tower of Divination correct?  Divination is finding out or revealing something correct?" 

Chill asks as he stands next to Krom as Krom points to the circular object with the floating eyes.

Kazri walks around the glass orb with sword and shield ready. She tries to count how many eyes are inside, and how many follow her.

Perception: 4

Kazri tries to count the eyes but they move around and she quickly loses track of which ones she has counted and which ones she hasn't.  But there are at least a few dozen.  Some follow her while others watch the others.

As she goes around she sees that the stone plinth upon which the orb rests is engraved with instructions written in Draconic which Rhogar can translate: “Ask and we shall find.”

"Some kind of undead I think." answers Krom while searching the room. "But since they are in the middle of this room, I suppose that they are somehow linked to the key of this tower." 

Religion 23

Krom recalls that a crystal ball filled with eyes is the symbol of Savras, god of divination, the deity of wizards, divination, fate, and truth.

Vellynne steps up behind Krom and Chill.

"This crystal ball could be used to find what we seek.  It could find the missing words.  Or even all of them." She says

Chill looks over his shoulder at Vellynne. 

"Have at it.  You are a mage, should be second nature for you to use such an artifact.  I wouldn't even know where to begin." He says

"Ask and find... ask and find..." Rhogar repeats a couple of more times once the plinth had been pointed out and translated. He then narrows his eyes at the crystal ball. "... Certainly a powerful tool. A powerful asset. I myself am tempted to be the first try it out, but... something about those eyes unnerve even me. But, if you would prefer not to, Ms. Vellynne, then I'll step up and 'try it out'. All I'd ask for is volunteers for the question itself. Something percise."

"They are indeed very unnerving. Try to not look at those eyes while you focus Rhogar." suggests Krom "As for the question, what about asking to know exactly how to obtain the key for this Tower? Or maybe, ask to know what was written on the missing part of that wall?"

"Xerophone here told us that to bypass the force field around the spire one must perform the eight steps of the Rite of the Arcane Octad outside the spire. The steps of the ritual are hidden inside towers dedicated to the eight arcane schools of magic. This message says third. So this is the third step of the eight steps. We need to know the whole message or we won't be able to complete the whole rite." Vellynne says.

Xerophon nods his head in agreement 

"I do not know what keys you speak of Krom." Xerophon says.  "You need to learn the eight steps of the rite to enter the spire."