Well, I did make it to Tower:27, and there I perished to the first enemy group.
It was a mob of succubi, yuki-onnas, and probably something else. Anyway, a bit before I had a feeling it would be a bit of a ballsy move to go without Calm and just Mindwatch. This did turn out to be a bit of an issue, even with Ammit having Discipline (replacing Swiftness); Ammit is really powerful, but it is a big liability for your party whenever she is charmed. I was running out of pure stones at this point, and so my run ended here.
To elaborate on what happened before then: Baba Yaga's Sanctum wasn't too difficult for me. The first shikome encounter wasn't great. I did manage to recruit a yuki-onna and modified her with Ninkasi's brewmaster, making her a partially supportive and partially offensive ally. The next few floors maintained a moderate level of difficulty, but nothing too bad for me. Ammit's Sanctum had a really rough first fight, though. It was a group consisting of a couple thrones back up by various rulers and angels, which would leave me with just an impundulu and shojo out. Fortunately, I did run into Ammit's group next, and I got her with a gold offering obtained within the previous few floors (how convenient!). I gradually managed to recover my party over time.
However, I did have a rough run in with a group consisting of rulers, powers, and dominions within the next few floors; I at least managed to recruit one of the dominions, and so I hanged on with a couple allies who were healthy enough to fight. I think I would also still have trouble with shikome groups, and my first encounter with wechuge was a rather rough battle. I've come to find them one of the most difficult late tower enemies to fight. In this game my party had good offense against them, but it was lacking in defense against their kinds of attacks. I managed to recruit an ijiraq on Tower:26, modifying it with my impundulu's ionic (I had noted by then my party's weaknesses were centered around the fire-ice-electric trinity). It didn't get to see much use with its given Wrath and Cleric's Mien, given that it was one of the last demons encountered before my final battle. I figure that I would have replaced my civatateo and dominion if I made it any farther.
My last upgrade was Alter Self; I actually invest in agility for quite a while, given the use of Ice Dart early on. I did find a brand early on that would give some extra speed and vitality in exchange for having agility equal to or above a certain amount, but I was still increasing agility for a while after disregarding that brand. When I started boosting magic from the reallocated stats, I started to do lots of damage; even Cold Embrace could do quite a bit of damage alone, most notably against enemies with a defense debuff. Icebreaker did trigger sooner often, and even Malice itself was a good finisher in several fights.
As for my brands, I did use that one > level 24 for +2.8 extra SP per turn one for a bit before finding a brand that would reduce SP costs by 5 in return for less cunning. This was a great brand for my PC, given that it meant free Malice attacks all the time and my other attacks were so cheap that I would hardly have anymore SP issues, so long as my character wasn't infected. I still held on to Mobility, though, which I think was still helping a bit.
>Icebreaker is one of my favorite skills
It does have an interesting synergy with attacks like Snuff Out, I've found: it pretty much bypasses Diehard, given that the initial attack does significant damage which is likely to force Diehard into cooldown, triggering Icebreak to cause a swift death. It helps out in those fights against gorgons, at least. I figure it could also be a decent anti-summoner combo, if it ever comes up.
>countering status conditions
I don't get them very often but I do think the "iron x" abilities are actually pretty good. I've found Iron Mind especially useful, as the benefits of Charm and Panic being halved is really noticeable. It would have likely been good for my ended game on Ammit at least, on top of Mindwatch support from my dominion. I think the aura abilities can also be pretty useful. Of course, they're really strong with copy spam, albeit it's probably just worth having it on two characters (one likely being the PC). I think uncurse aura in particular is really good (its inverse is also incredible, especially against Guadium users and self-buffers/cry buffers). The Anti passives are perhaps the "trickiest" lot, but I can at least say that Anti Hex on a power is pretty noticeable now that bruchas can inflict hex. I figure those really depend on play style the most, and the resistances and immunities within a party, of course. For instance, I can imagine Anti Infection being a great means of basically always having SP recovery on a character that isn't body-immune, and some others like Anti Chill do deny a lot of attacks and passive effects like the "lord" abilities. I haven't experimented much with them yet, but I figure they can make certain fights easier to weather by entirely denying options to the enemy, if you're willing to invest in such abilities.
Anyway, this was a pretty fun run. I think I'll try to finish that ole "Pursue" game I still have and see how it goes. I'll probably be playing the Tower:30 build within the upcoming week once that game ends, success or failure.