We've reached what's probably my favourite KotET chapter... but more on that later.
With the fight on Iokath wrapped up one way or another, things seem to have calmed down a bit, except that Vaylin having retaken control of the Gemini droids also means more attacks on Alliance patrols and outposts. Since she's in a celebratory mood, she wants to throw a grand party, with its main event being the execution of some Zakuulan rebels. What she doesn't know is that her "party organiser", a guy called Indo Zal, is a traitor too and has gotten in touch with the Alliance to disrupt the festivities and free his compatriots before they can be killed.
The plan is for Lana and T7 to slice the security grid while you and Theron infiltrate the party dressed as Knights of Zakuul and plant ion charges around the building that will allow you to break all the prisoners' shock collars in one fell swoop. This serves as a fantastic advert for the Zakuul Knight armour set by the way; I thought my characters looked really snazzy in their disguises! Wonder if that increased Bioware's sales of that particular item set... I was kind of tempted myself, but still couldn't think of a way that wearing this set would make sense for any of my characters outside of this particular scenario.
Anyway, you and Theron successfully infiltrate the party and pick up the ion charges from Indo, and then comes the part that I love but which I could also see people hating: a puzzle section during which you spend your time running around the building, trying to get access to all the locations where you need to plant the charges. This involves the solving of some simple problems, such as pretending to be the food delivery person for the guards to gain access to their barracks. If you get stuck, there is an in-game hint button you can click. I'm not going to describe all the steps in detail here; if you need a walkthrough I can recommend Fibrojedi's for the main mission and this post by Calphaya for the super secret bonus mission that isn't even displayed.
While you plant the charges, we're treated to a scene of Vaylin talking to an Anomid via holo, who assures her that they are close to freeing her of her "weakness" (aka the conditioning). Indo walks in on this conversation and manages to immediately look highly conspicious... one has to wonder how he managed to fool Vaylin for as long as he did if merely walking in on her in the middle of a conversation is enough to cause him to blow his disguise. Unsurprisingly, he gets added to the shock collar squad.
You finish planting the charges just in time for Vaylin's speech, which is when you decide to ditch the armour and crash the party. Vaylin just has enough time to throw the rebels into her beast pit before you activate the ion charges and say the magic words to trigger her conditioning. Right on cue, an unknown shuttle also attacks the building, and out comes... Arcann, accompanied by some soldiers. In the ensuing panic, with people running all over the place and various blast doors getting shut, you manage to jump into the beast pit where Indo and the rest of the rebels are unarmed and exposed to various beasties (though if you did the secret bonus, all but the rancor will be friendly to you). You defend and free them and then have the option to order them to serve as your cannon fodder or encourage them to get to safety.
Vaylin has fled the scene to the sky deck, where she is confronted by her brother and they fight. As soon as you arrive, Vaylin uses a speeder to make her escape, leaving you to confront Arcann alone. Interestingly, he's very different depending on whether you chose to help or kill Senya in chapter one. If you made the kind choice, Arcann himself has turned to the light side while he was away. As a gesture of how much he's changed, he's even got rid of his face mask. (I kind of thought he needed that thing to survive but I guess he just wore it to look edgy and hide his scars? Unless the ritual on Voss also healed him physically so that he doesn't need the mask anymore.) If you killed Senya, Arcann is more or less his old self only even madder and angrier.
Redeemed Arcann vs. "Darkann"
Light side Arcann will pledge his allegiance to you and helps you fight off some Horizon guards. Dark side Arcann wants to fight to the death as usual, but this time you finally get to kill him. (This is what, your fifth attempt to do so?) Since there are lots of holo cameras watching, you also get to frame the event in a light or dark context regardless of which version of Arcann you're dealing with. Either you're a benevolent rescuer, backed by the former ruler / ridding the planet of the previous tyrant, or you're showing off your power, having the former ruler kneel to you / killing him on camera to demonstrate your might. Also, Valkorion chimes in to make some douchey comments to his son either way. The bastard.
Vaylin has escaped to her flagship and orders the fleet to bombard the site to kill everyone, but Lana and T7 help you escape. You return to Odessen victorious, either with a former emperor in tow to support you from now on, or having absorbed his strength while killing him (as commented on by Lana and Valkorion). Either Arcann or Valkorion also comment that Vaylin remains a challenge and won't remain chained by her conditioning forever. And indeed, the chapter ends with the player watching her ship arrive above a dead world where she plans to break her chains.
I absolutely loved the puzzle section of this chapter. Adventure games were the first PC gaming genre I ever fell in love with as a teenager, and the tasks you have to take care of in this chapter certainly harken back to that kind of gameplay. Now, since this is quite different from what we usually do in SWTOR, I could also see people hating it, but I would hope that only few would have quite such a strong negative reaction. Even on the forums I only found this post by a guy proclaiming that this chapter had "chased him off", but most of the replies seemed vaguely bemused by this rather than in agreement. Bioware actually does have a long history of inserting random puzzles into their content, yet they remain infrequent enough that it's still a surprise every time it happens. I think this chapter does a good job in terms of setting expectations though, as it's explained from the start that your goal is to succeed via subterfuge instead of fighting, so you avoid the pitfall of suddenly running into a "puzzle wall" in the middle of a combat mission.
I also love the hidden bonus mission. It's cute, rewards people for paying attention beyond what it says on the objective tracker, and especially on the harder difficulties it's actually quite handy to complete as well - while your "pets" aren't particularly strong, effectively having four extra "companions" following you around and helping you fight things is definitely useful in terms of dps.
Arcann coming back in two different ways depending on your choices in chapter one is also really well done and undoubtedly one of the better ways in which Bioware managed to live up to their "choices matter" mantra. Initially I wasn't sure whether I liked light side Arcann because in my opinion he comes across as a bit odd - even if you helped Senya, he was confused and hostile the last time you met and his change of mind isn't really explained. However, he grew on me over time and I found his portrayal actually kind of realistic in the sense that he clearly went through a life-changing experience and is now totally focused on it - like someone who converted to a new religion or otherwise changed their lifestyle, found that their life changed for the better afterwards, and is now trying to prove his devotion to his new way of life at every opportunity. Incidentally, the SWTOR Facebook page revealed the other day that 76% of players so far have chosen to redeem Arcann.
Finally, I thought that Indo Zal was a pretty good character in the sense that they managed to give him a fair bit of characterisation for someone who was only just introduced and remains a minor character throughout.
The only negative thing I have to say about this chapter is that the layout of the building feels like it's designed to artificially prolong the chapter, especially towards the end when certain doors suddenly close without explanation, forcing you to run all around the houses to get to where you need to be. I did love the overall atmosphere though.