It looks like the Magister didn't load into the map? If he's not there, and the dialogue option isn't triggering, than you might have to re-load from the start of the final area (there should be an auto-save at the elevator).
I'm guessing this happened right after you entered the final room? And not after talking to the Mangister?
1) Device? / Operating System
2) Version of game?
3) Anything special about your version of the game?
4) Did you quit / re-enter the game at any time while on the final part of the arc?
2) last version
3) nothing i have paid for it
4) bro it was very difficult for me to get to this place, I don't think I will be able to do it again,
I was watching it on YouTube and I saw a video saying that I can't have a good ending because I didn't kill NPC Valeran, which is on the dragon coast ... I think that's not fair, I have to start a game from scratch to get a good ending now ...
5 sorry for it, my english is not good, i used google translate
Having Valeran ALIVE at the meeting helps get both a Good Ending, or a Peaceful Ending. Technically speaking, you do not NEED Valeran alive for any of the good endings, but having him around help get enough debate points to either get the peaceful ending, or get some help fighting the final boss. See here for more details.
Sorry. I don't think there's another option. If the NPC's don't load correctly with the map, there's not much to be done about it. It happens very rarely, and most the of the time when it happens it's on a map that's easy to simply re-load (stay at an inn etc). Really sucks it happened on the one map you can't re-load.
Do you have all the arc equipment? The arc weapons, armor, and belt? Those help a lot with the final area. Using arc weapons with batteries so the EMP attack happens makes short work of the area.
Also, did you rescue you're sister? She's hidden on the final floor? She can help fight the area if you're really struggling.