Everything comes to a head in what has become standard spectacular "Spartacus" fashion in this resolution to the prequel mini-series. Vengeance and glory are the order of the day, as well as a glimpse into the future as the writers (and the fans) turn their eyes to the follow-up to "Blood and Sand".
The revenge against Tulius and Vettius had been a long time coming, and Lucretia set them up beautifully as the scapegoats for the deaths of Titus and Mellita. At that point, the story was relatively straightforward: Batiatus wants blood, and his allies provide. What was surprising was Solonius' role in the vengeance. After all, the audience knew that Batiatus and Solonius would have a major falling out sooner rather than later, and this seemed to be the right time and place.
But the writers had something far more insidious in mind, playing on the penchant for characters to take maximum offense to thoughtless insult. We've already seen it happen with Batiatus and Lucretia, and now it comes to a head with Solonius. Suddenly all those biting comments come back to haunt Batiatus, and the genesis of the bitter feud between former friends is revealed.
The nice thing is that it makes sense. Vettius' ludus was the main competitor for Batiatus' enterprise in Capua, and it seemed odd that Soloniuis would simply generate a contending ludus in a matter of months. His wholesale takeover of Vettius' assets, however, explains the seeming discontinuity. And it also serves to bring immediacy of context to the contest on the sands during the opening games of the new arena.
Other little things were addressed in this episode. Lucretia's affair with Crixus takes a big step forward, and Naevia takes her place as Lucretia's body slave. Diona meets a cruel end in the arena after being captured. It's made abundantly clear that slaves in the Roman world are nothing more than pawns in the Great Game. But as it should be, the majority of the big moments come in the arena, as we get to see the final twists for Gannicus, Crixus, and Ashur.
While one could definitely point out that the bloodshed and violence of that final act plays into the subversive societal commentary at the heart of the series, the entire sequence was underscored by the character dynamics. The editing was careful to focus on each character whose fate was important to the story. The interpersonal conflicts informed what would have otherwise been empty spectacle.
Ashur has never been a sympathetic character, but "Gods of the Arena" has really demonstrated how loathsome he is. The writers made the audience cheer for Dagan to get his revenge, even as it was clear that Ashur was going to survive. Yet at the same time, Ashur does survive to the near-end of the final match, which is better than he should have done. The irony, then, is that he finally demonstrates some skill in the arena, just to have all that potential ripped away when Crixus hobbles him.
Once it became clear that the writers were not going to have the Gannicus/Crixus throwdown that they both wanted, it was hard to determine how they would get themselves out of the hole. Crixus' toss out of the ring was a bit too easy, but the rest worked brilliantly. Gannicus' freedom allows for his return in the follow-up to "Blood and Sand" while explaining why he was never mentioned previously.
The upshot is that Gannicus can return, and this backstory with implications for Crixus and Oenomaus would necessarily factor into the plot at that point. With the change in actors for the roles of Spartacus and Naevia, it would help the production gain a sense of continuity to have yet another familiar face.