Here I'd like to entertain what is perhaps an unorthodox theory: that Iris, in collusion with Amon, planned Dekar's "death" in the Karlloon North Shrine.
Before I begin, a few facts established before and during the party's visit to Karlloon:
Maxim and co. sit back and indulge this tendency of Dekar's
Certainly the Sinistrals are aware of this, through Idura
Idura and Iris were communicating prior to this point, as revealed by one of the kidnapped girls in Narcysus — and Iris told Idura she was going to Karlloon, implying that he was to follow
Another "great ball of light" was spotted landing in the Karlloon shrine at about the same time that Iris had arrived there, as reported by one of the townspeople in Karlloon; later, Idura indirectly reveals this ball of light to have been Amon, who dismissed him as his servant
And that brings me to the events in the shrine. When the party encounters Idura, he's angry because Amon fired him for all his failures. He tries to fight everyone in revenge, and of course he loses. This raises the question of why Iris would point Idura in the direction of Karlloon and this shrine — just so Amon could fire him? That could be done anywhere.
A dying Idura claims that the party won't leave the shrine alive. The entire scene with him turns out to be a gateway to something more important, and strangely conspicuous. Iris is waiting in the back room, claiming she was kidnapped by Idura. When Maxim asks why Idura would do that, Iris replies vaguely, "I do not know." She is quick to change the subject and thanks the heroes for rescuing her. Suddenly, the shrine starts to quake. Selan tries to cast Escape, but the spell is blocked.
This is the closest Iris ever gets to the magic device.
Iris tells the party that something is generating the magic negating Escape, and that it must be destroyed for everyone to leave. Dekar takes the reins again, being the warrior most eager to do the job. The party eventually finds a large ball similar to what generated the monsters in the cave to Bound Kingdom. Iris says it's the cause of the magic blockage. She and Dekar run up to it. Oddly, Iris never gets too close to the device (see screenshot, left). After Dekar breaks it, he and Iris make to leave — and Iris, who remained close to the stairs the entire time, has no problem reaching a safe distance before a monster appears, catching Dekar by surprise. Then the ghost of Idura appears, with more monsters. The timing is perfect. Iris is able to reach the rest of the party and warp them all out of the collapsing shrine, leaving Dekar behind.
Idura could have appeared at any time. Instead he waited for Dekar, who was goaded by Iris and allowed by Maxim, Guy, and Selan to break the magic device and thus put himself in harm's way. It is not implausible to say that this scenario was cooked up by Amon and Iris as a way of playing on two characters' inherent flaws, thereby disposing of them both. Idura was defeated before and would be again. Iris — aka Erim — may very well have granted him one more chance at existence so he could take one last swipe at Dekar, something he would not have been able to resist. And Idura is clever enough to act at the right time. And Dekar, slow as he is, is easy to lead on, always jumping head first into dangerous situations.
But why would the Sinistrals want to take down Dekar, you might ask. A possible answer is that he was rumored to be the strongest man on earth. At the very least, he was the strongest member of Maxim's party. This would pose a problem for the side of evil in the long run — and as Dekar's return in Portravia proves, it was more of a problem than they had ever reckoned.
