Assault on the Wizard's Tower

We decided to leave the town, heading towards the wizard's tower that had animated Borris to life. As we left, I couldn't help but feel a little lost. I know why we're here. I know we need to stop... I can't write the thing's name or else my journal will freeze. But even so, how do we get there? Who do we talk to? How do we even stop it? I'm hopi9ng the wizard will have some explanations if he still lives.
 
Reaching the tower was easy, but from the air it seemed to be guarded by robed figures, and there appeared to be blood on the ground. Aerilyn decided to play a song of some sort to intimidate them, and while I wasn't sure how effective it was (at least until later), it had an amazing beat! We decided to land after changing direction but were discovered anyway as we walked toward the tower. We fought a group in hooded robes, who ended up being able to manipulate blood somehow. They looked like monks or something, but we couldn't see their faces. After some effort, we managed to take them out. After incapacitating one, I discovered that it was undead. We dispatched it shortly after, Kahla carving that... thing's name into its arm, freezing it solid. For some reason, I keep being prevented from killing the undead. I'm sure it's just a coincidence, but it's starting to frustrate me. It's one of my purposes in life to destroy the unholy, along with sustaining life. It's my duty as a cleric of Chauntea.
 
After dealing with that group, we continued to the tower. The group of fighters we had seen before were staring at the sky, no doubt distracted by Aerilyn's song from before. We debated on what to do but eventually settled for my suggestion to disperse the group using my ability to turn the undead. After scattering them, we ran into a puzzle at the front door. A scale, encased in glass, stuck out of the wall. A small model of the tower sat on one side, and a pile of rocks on the other. A small message was written to the side, mentioning that tipping the scales would reveal the key (I think?).
 
We spent... more time than I care to admit on this puzzle. I think its flavored my viewpoint on wizards very negatively, and I do not wish to go into everything we tried to get it to work. Eventually, through wild magic, Cordelia managed to teleport inside and let us in.
 
I'm not sure what awaits us in there, but I hope it's worth all of this trouble.