Now that you're done dealing with Irovetti's threats, you'll have to turn your attention to Nyrissa... more specifically, your plot to infiltrate her dreams. To recap (because it's been a fair bit of time since this quest started), you should have been been approached by Linzi and the storyteller after finishing the Rushlight Tournament with a scheme about invading Nyrissa's dreams and finally striking back at the fey. After that there was little you could actively do to further this quest aside from completing a project related to it, then waiting for Linzi and the Storyteller to finish their preparations for the ritual... during which time you should have completed the three aforementioned quests to blunt Irovetti's assault.
Not that the completion of the former quests will necessarily neatly coincide with with progress on this one, mind you, there still may be a significant wait involved, during which time you can complete other side quests or exploration. Eventually, however, you'll get an invent informing you that the Storyteller is ready to perform the ritual. After this you can, at your discretion, talk to the Storyteller and pick the dialogue option "Everything is prepared for the Dream Ritual. I am ready.". You should probably make a hard save before starting this, however, as you'll only be able to enter the dream realm with your protagonist and Linzi, so preparation is key... and a bit of trial and error may be involved.
Battle: Defaced Trio
When you appear in the dream realm make your way northeast until some ghostly nymphs appear, cheering on their beloved sister. Talk to a ghost named Evindra to witness a scene of the past - apparently Nyrissa in happier times, when she had loftier, more benevolent goals. When you get a chance to respond, say whatever you wish. Regardless of what you say, you'll end up having to fight three Defaced Sisters.
Like their normal counterparts, these twisted fey will attack with an Agonized Scream, which you should be immune to. You won't be immune to their Stunning Glance, however, so if your Fortitude Save is suspect, buffing with Freedom of Movement may prove helpful. With those attacks nullified, you still have to watch out for their Tortuous Touch, a touch attack with a moderate Attack Bonus that can inflict damage and ability damage. Defensively, the Defaced Sisters do you no favors, having a high Armor Class. On the plus side, their Will Save is fairly low, so Linzi might achieve great things with Phantasmal Web or similar debuffs.
Defeat the Defaced Sisters and you'll get a warning from Linzi about monsters lurking in these dreams, after which you'll appear near where you entered, healed and ready to go. Ahead of you you'll find Nyrissa locked in combat with a Lesser Jabberwock, a battle there's no need to involve yourself in. Continue northeast to find a familiar scene of Nyrissa being chastised by some Will-o-Wisps, along with other characters, the most prominent being The Lantern King.
Watch the scene play out, and when you're back in control talk to Nyrissa and make what judgment you see fit, after which she will again angrily retaliate by sic'ing some Will-o-Wisps on you. These monsters dispense with debuffs, and instead perform melee (touch) attacks, albeit with a high enough Attack Bonus to all but guarantee a hit on any but the most dexterous of characters. Fortunately, their weakness is that they deal electrical damage, so if you can protect yourself against electricity somehow (Potions of Resist Electricity, for example) you can mitigate much of their damage. Defensively, their Armor Class is nothing special, and they're HP don't give them a great amount of staying power, either.
Battle or Book Episode
After this second battle you'll again be whisked away, this time to a new location where Nyrissa argues with some other Nymphs. Apparently they're looking for some "Briar", which Nyrissa believes is in the Stolen Lands. Talk to dream-Nyrissa and she'll illuminate the situation, giving you insight as to what this Briar is, and how it all plays into her curse. Her systemic destruction of mortal realms in the Stolen Lands.
You can actually avoid a confrontation this time around, if you pick your words wisely and are [Good] aligned. Picking the dialogue option "Whatever the others did to you, we're each responsible for our own crimes." or "The only thing that seems to have left you is your mind!" will provoke Nyrissa into siccing two Defaced Sisters on you, while the dialogue option "What exactly were you looking for?" just gets you some information. On the other hand, if you respond with "Your kindness? Your soul?" you'll get a [Good] option that'll bypass the aforementioned battle. More importantly, if you pick the [Good] option and avoid a fight you'll be treated to an Illustrated Book Episode, the outcome of which is trivial, but it'll still be covered under the heading "Nyrissa's Dream Illustrated Book Episode", below. Otherwise, skip ahead to "Battle: Nyrissa's Minions"
Nyrissa's Dream Illustrated Book Episode
- ...a magnificent and powerful dragon!
or ...a fossegrim - a regal and handsome representative of the fey people!
or ...a tall, slender, sprawling tree!
You'll start out by picking what form you want to take for this silly dream, which can effect the outcome by determining what skill/ability checks you'll have to make later. For the dragon you'll need to pass a [Constitution 20] check, for the fossegrim you'll need to pass a [Charisma 20] check and for the tree you'll need to pass a [Lore (Nature) 30] check. Pick whichever one you're more likely to pass, as this is the most important checked option in the entire Illustrated Book Episode..
There are some inconsequential choices, too, which mostly just earn you XP, and for this the dragon is the best choice, provided you can pass an [Athletics 35] check. The rest of the possible skill/ability checks give a relatively small amount of XP, making them less important.
- ...a flying inkwell!
or ...a shaggy giant with a huge club!
or ...an unknown but very fluffy creature!
Whatever you change Linzi to isn't very consequential, all that really matters is you succeeding at the important skill/ability check, which is determined by what you pick in answer #1.
3a. [Athletics 35] ...taking off!
or [Constitution 20] ...breathing fire!
or [Intelligence 20] ...making someone their minion with the power of their mighty mind!
You'll get these options if you picked ...a magnificent and powerful dragon! for the first option. Of these three options, the [Intelligence 20] choice gives you a small amount of XP, the [Athletics 35] option gives you a considerable amount of XP and [Constitution 20] will result in Linzi spotting "an alluringly shiny casket" in a "snow-covered glade" which she makes certain to remember for later.
3b. [Charisma 20] ...charming an attractive being!
or [Charisma 20] ...changing reality!
or [Intelligence 30] ...making someone their minion with the power of their mighty mind!
If you picked to turn into a fossegrim during the first option you'll get these dialogue choices. The [Intelligence 30] and [Charisma 20] checks both get you a small amount of XP, while the [Charisma 20] check will result in Linzi spotting "an alluringly shiny casket" in a "snow-covered glade" which she makes certain to remember for later.
Note: After this dialogue check you'll get a choice where you have to pick between ...building a stairway to the sky! or ...dropping a lake from the mountain!. It doesn't matter which one you choose.
3c. [Charisma 20] ...charming an attractive being!
or [Lore (Nature) 30] ...making thousands of flowers bloom!
These are the options you'll get if you chose to turn into a tree, for whatever reason. Again, the [Charisma 20] option, which is identical to the fossegrim transformation, has the same outcome. Picking the [Lore (Nature) 30] will result in Linzi spotting "an alluringly shiny casket" in a "snow-covered glade" which she makes certain to remember for later.
- "So, this is your realm?"
You'll get this option along with a generic [Attack] option, the latter of which will end the dream, while the former will continue with two sets of questions you can select from to possibly influence Nyrissa, as follows:
- "This is a crazy plan. Give it up, or you'll lose everything."
or "It's a good idea. Too bad this is all just a dream."
- "Yes. You deserve your fate."
or "No. Do not succumb to despair and evil. Only then you will have a chance."
Battle: Nyrissa's Minions
After the fight with the Defaced Sisters - or the Illustrated Book Episode, if you were able to skip the fight - you'll appear in a chamber with multiple ghosts of Nyrissa consorting with her various minions, dead or alive. These include the Stag Lord, your protagonist, Tristian, Armag, and yes, even Irovetti. That answers the question about Irovetti's motivations, and with Nyrissa pitting him against you, you can expect your feud to only end when one side is utterly destroyed.
First things first, however, approach Nyrissa - the material-looking one at the top of some stairs - and talk to her. There's no avoiding a fight this time, as she'll set the ghosts of minions past and present against you. Of particular note are Tristian and your protagonist, who have similar gear and combat stats to the originals, so their threat level may vary a bit. Armag has the same high Armor Class he had before, and Irovetti will make a nuisance of himself by casting Overwhelming Presence, Displacement, Haste and Good Hope before attacking.
This may sound a bit overwhelming, but there are two mitigating factors. First, immediately after Nyrissa is done speaking you can run down a hallway to the southwest. You won't shake off all your foes, but you might deter a few of them from chasing you, and the fewer foes you have attacking you, the better. Obviously this strategy will work better if you're hasted and hence can flee faster than you can be chased (or faster than some enemies may aggro you, for that matter). Second, and most importantly, all these enemies have a pittance of Hit Points. One hit from almost any source - no matter how trivial - should be enough to dispatch them. Given that a mage protagonist can eliminate several foes with one Fireball, and Linzi can help out with any number of damaging spells, this shouldn't be too hard of a fight to win.
Vanquish your phantasmal foes, then Nyrissa will reappear, pathetically going through the motions of fulfilling the conditions of her curse. Talk to her again and she'll finally guess at your game, and seem oddly... pleased with your resourcefulness. As a reward for your ambition, she'll decide to throw her peacock - Irovetti, to her hound - you. Evidence of his crimes can apparently be found in Whiterose Abbey... not that his populace seems unaware of numerous crimes. In any event, you have no other viable leads, so leave the dream via the portal to the southwest to return back to reality, where there's a surprising lack of chatter to be done.
Nothing should distract you now from setting off towards this Whiterose Abbey, as the longer you delay, the most Irovetti will damage your kingdom stats via regularly recurring "Pitaxian Influence" events.