I finally came to the part where Halsin is kept prisoner but late enough to find him dead.. and there's no way to revive him whatsoever. This is quite frustrating, especially when you realize it's a full story and quest that will go missing througout your whole playthrough... I can understand Larian decided so in order to create different and believable stories but this would leave players unwlling to get over one important character to start over the whole game, after more than 40h ?! I don't get it, why didn't the studio leave the opportunity to get him back through another quest instead of quitting his story so sharply leaving players with such disappointment ?
If you go into the shadow cursed lands, or the Mountain pass before rescuing Halsin then he dies.
If you go into his prison area and then leave it can also end in his death.
Without Halsin you cannot