Looking over the vortex with his new [Mana Vision] skill, Cain can see that it is missing something, and that missing something is what is making it unstable. For now, he doesn't know exactly what it is though, so fixing the vortex is beyond him. The principles of Spell Crafting say that it can be modified though, which means he will eventually be able to fix it, or at least stabilize it and hopefully remove the people that are trapped inside.
If nothing else, maybe he can modify it a little and turn it into a dungeon.
At the moment, the best he can do is an experiment. The damage looks to him like the vortex has been pulled apart, leaving it in barely attached pieces. The obvious first thing to do is separate them and see if the whole thing collapses. Cain pulls at the strings of runes, trying to break them at a weak point by destroying the runes, but the harder he tries, the stronger they get. Once he stops exerting pressure, they seem to relax back to their original form though.
