After a number of episodes focusing on stand-alone concepts, the season arc comes back in a big way in this penultimate episode for the series. The name of the game, as usual, is plot progression, even when it requires severe willful suspension of disbelief to accept the logic that allows for that progression.
No matter how well they leave the door open, this felt like a way to take the ridiculous Ba’al plot thread and bring it under control. The ending mitigated that measure of control, but we now have less Ba’al clones to worry about, and that’s a good thing. Given the age of the series and the constant possibility of cancellation (which is now coming to pass), having such a massively open-ended plot element lingering the background was simply not a good idea.
That’s why bringing Ba’al into the prelude to the conclusion of the Ori arc was a genius move. It helps make sense of Ba’al’s actions since the fall of the System Lords, and it’s the kind of leverage he would try to find and utilize. It also allows the writers to complicate the capture of Adria, which might otherwise have been a bit too easy.
Unfortunately, after setting the stage for a final showdown over the solution to the Adria problem, the writers toss a major plot convenience into the mix. Despite taking precautions on more than one occasion to keep an anti-Prior device around Adria, they completely blow it during the most important moment. If one of those devices had been in the room when the toxin was being administered, Adria would have been gone and, if Ba’al and Adria are to be believed, the Ori fleet would be without Ori and Orisi.
Instead, Adria is able to ascend, which is a nice set up for the conclusion of the arc in “The Ark of Truth” film, if nothing else. I’m just not sure that the writers took the most logical path to that end. More than once, the characters mentioned Adria’s eventual ability to overcome the anti-Prior device; why not use that plot point to explain her ability to ascend at the end, even with one of the devices in the room? A minor change, but one that switches plot convenience with plot payoff.
That final act is really the only weak link in the episode, despite my annoyance that the Ba’al plot thread was kept open when it could have been easily closed. It’s enough, however, to keep the episode from achieving its full potential.