Blai would offer some more palatable form of address but he's drawing a complete blank here. Select-but-with-distaste it is, he guesses. "Very good, thank you."

And on.

They are jumped by yet another dretch on the way to the Tower of Estrod, but dispatch it easily.

The Tower of Estrod has clearly taken some damage; the roof seems to be entirely gone, and some parts of the walls have crumbled. Still, there's something resembling a main entrance in the form of a hallway leading to the central tower structure, even if the entrance is less a "door" and more a "large hole in the wall."

No demons or cultists obviously prowling the outside?

Not at the moment! 

(The only Evil aura Seelah detects at the current distance is the Count's.)

Well, then they can try tentatively stepping in.

Like the exterior of the tower, the hallway has clearly taken some damage. Some of the tower's paintings still hang on its walls, and some of its statues are still standing, but there are also informational plaques with no matching painting, and paintings that are so badly damaged as to have been destroyed. On the other end of the hallway is a large metal door, presumably leading into the central tower; a large pile of rubble near the door has been arranged into something resembling a staircase to the second floor of the central tower.

As he steps into the hallway, a ghostly armored figure with large feathered wings emerges from the wall to his left. "Kenabres burns... the city that should never have fallen. Fate shows no mercy."

"Ser?"

She's looking at the figure a little wonderingly. "Not Evil, Select."

Another ghostly figure steps forward from the wall to his right, this time a human woman. She turns to face Blai. "Clouds may veil the stars, but nothing can hide the light in someone's soul forever. And I see this light in you."

 Another figure, likewise a ghost resembling a human woman, emerges from the right. "We will stand shoulder to shoulder with you against Evil."

A fourth figure, an angel, emerges from the left. "I hear the echo of a familiar voice, I feel the warmth of my kindred flame. My brother, we will help you." (She does not remotely resemble any of Blai's actual relatives.)

 The four figures raise their hands in the air and chant for a moment. When they conclude, Blai can make out the fine details of the paintings in this room more crisply, and his steps feel lighter.

"Fascinating! You seem to have manifested a pair of wings. Has this ever happened to you before?" She turns to the ghosts. "And you! What criteria do you use when assessing whether someone's soul contains light? Is it purely based on alignment, or are there other factors?"

(The ghosts do not answer her.)

"None of them are Evil. I didn't think angels could leave ghosts, but..."

He has wings?? What is he supposed to do with those? He looks over his shoulder to check.

He does! They're white and covered with feathers; they arguably resemble Lariel's wings, in the sense that someone who had only met a handful of humans might say Blai's arms resemble Nenio's.

"What is it you want of me, please?" Blai asks the ghosts.

The third figure: "Stand—" (it flickers for a moment) "—against Evil."

 The second figure: "Nothing can hide the light."

"I see we have ourselves judgmental spirits."

The third one, again: "Stand shoulder to shoulder."

There's a longer pause, and then the fourth one speaks. "We are the echos of the first crusaders. You are the echo of my brother, my twin, the one I thought was lost forever. But I hear another echo, one I have never heard before, and I fear for it. The path before you is both wider and narrower than you could have imagined."

"Select Artigas, I suspect that these spirits may be some form of imprinted memory, more than conscious will. I will attempt to commune with them if you wish me to, but I do not know if I will be able to hear anything more." Her right hand curls around the amulet at her neck.

"It seems - pertinent, please go ahead."

"Clouds may veil the stars," says the second spirit.

Camellia retrieves an off-white powder from a pouch and sprinkles it in a circle around her. She kneels on the ground, palms against the floor, with her eyes closed.

Scribble scribble scribble.

"This place was a sacred site to those who guarded the past," she says after a few moments. "Many memories were preserved here, and it is those that you see before you. But I can hear the voices of the spirits of the slain, calling out in desperation. They cannot find peace while the monsters who desecrated this place still draw breath."