Strategy with Aksha?

I try to paralyze her, break the curtains and use a maximum of light spells on her and her minions + 1 flaming sphere. The first rounds are focused on Aksha and then her minions. I sometime need 2 rounds to paralyze her, but most of the time (90-95%), it works.

Aksha is a DPS race with kiting. Kill Aksha first with a tank in the light where she spawns. If she casts darkness just disengage into an area where she will fight in light that you make.

So, I popped invisibility on my party before opening the door, opened up combat with surprise sneak attack. Concentrate on her and killed her second round before she could act. That worked for me on pretty much every boss fight really.

This fight is balanced really, really badly.

I ran with a four dwarf Battle cleric setup. Made sure I hit level five before starting this area. When I got to Aksha room I talked to her and passed the checks which gave 1600 exp. Then I broke the windows cast 4 daylights and all 4 spirit guardians. And light on all my weapons. She didn't last two rounds. Then I did all fights using 4 spirit guardians and with each cleric sporting fireballs all fights after was easy as cake. I just kept the clerics all grouped up used crossbows and fireballs for the ranged and let the melee come in and destroy themselves with the spirit guardians. 

Easy peasy 

Ghoul touch poison works on all of the vampires, or whatever they are called - they don't use Legendaries when paralyzed. That turns the fight from challenging to a turkey shoot.

I've finished the game twice now.  This is the hardest fight in the game by a lot (with different group compositions).  And, there is NO way the designers intended that to be the case.

A lot of the things that make this fight harder would be how spectacularly broken things are. You may not get hunter's mark or colossus slayer damage included in a turn. The bane spell buffs the enemies instead of debuffing them. The daylight spell is virtually entirely worthless somehow in a fight with vampires and it will not dispel the magic darkness that gets summoned (a core feature of the spell in the pen and paper game) and the magic darkness will basically overwrite the daylight in a sphere of influence.

• Any form of light is key.  It's easy to do that by breaking windows (with spell damage).  Having the vampires in bright light does 10 damage to each per turn (3 vampires in the room so a single bright light may be worth 30 total damage each round in direct damage to the vampires).  I cant remember if the vampires in this game have vampire passive regeneration as they do in the pen and paper game but daylight in the pen and paper game cancels their passive regeneration and any source of bright light would do that in this game (in the pen and paper game they take 20 damage per turn from daylight and it also cancels the 20 damage per turn of passive HP regeneration).
• Don't try the fight at level 4.  I feel pretty certain it can be done.  But, hit points, damage output, saving throws, and where applicable spell effectiveness goes up at level 5 for all classes.
• Focus damage on a single target at a time.  You can either burn the adds or go directly for the boss.
• She has damage reduction to non magical attacks.  I can't recall off the top of my head if poison works on her.
  • Guardian spirits is huge (3rd level spell slot for clerics).  This will deal passive damage.  Get in the habit of casting that as soon as combat starts and run next to the tank.  If you aren't a battle cleric it may be worth while to wear a shield in one hand and only cast spells in the other rather than to hold a weapon in one hand and no shield so you can still cast spells with a weapon in your hand.
  • Spiritual weapon is useful (2nd level spell slot for clerics).  This will deal damage with your bonus attack (it's concentration and doesn't work at the same time as guardian spirits).
  • Flaming sphere can be challenging to use.  It creates bright light and can also be used to deal on going damage, but it will damage allies adjacent just like it will damage adjacent enemies.  Aksha will hover directly above party members making this spell less useful.
  • Even though, mechanically, cantrips are typically inferior to ranged weapon attacks for wizards and clerics the resistance to non magical damage and the access to magic weapons at this level means cantrips will likely be the standard way to go for these characters.
  • If Aksha is attacking a single target you may want to do everything you can to reduce the incoming damage to that ally.  That could mean equipping a shield instead of a 2 handed weapon if possible.  That may also mean taking a dodge action instead of trying to deal offensive damage.
  • Anything you can do to maximize your damage output will help with your characters attacking with non magical weapons.  That means maximizing sneak attack hits and such.  Don't miss your bonus weapon attacks if you have follow up strike with 2 handed weapons, or if you're wielding two weapons.
  • I haven't tried this yet, and I'm guessing it's broken in Solasta and won't work as it should according to 5E rules ... because so much else is ... but the third level wizard spell bestow curse can be used like a worse version of the first level hex spell.  This would mean that if you are within touch range of Aksha and you bestow the damage curse each time Aksha takes damage from your wizard's spells they take an extra 1D8 necrotic damage (unsure if Aksha is resistant or immune to necrotic damage).  This turns magic missile into a powerhouse spell, especially for the shock arcanist.  A third level spell slot casting magic missile would fire 6 magic missiles. Each does 1D4+1 force damage plus 1D8 necrotic damage and automatically hits.  That averages to 8 damage per missile (2.5 + 1 + 4.5) so a third level magic missile would do, on average, 48 damage.  This combination concept is why warlocks like the wand of magic missiles so much in the pen and paper game.
• Some people are using a trick where you change equipment every other round to wear a shield.  So, you attack with two weapons or a 2 handed weapon and do extra damage.  Then you equip a shield for the AC increase and end your turn.  During the next turn you can interact with one item for free so equip your 2 handed weapon or your offhanded weapon and do your maximum damage.  You cannot wear the shield again this turn because you already interacted with an item.  On the next turn you can take your turn as normal and then equip the shield again before your turn ends and the process repeats.
• The darkness Aksha creates doesn't last forever.  You can kite her out of it and avoid attacking her with disadvantage.
• If you happen to roll well and get into the room without the fight starting immediately know that if you click on virtually any loootable objects in the room you'll trigger the fight.  So, if you still want to loot the room you can take an extra moment to prepare for the fight or you can bypass it completely through lucky out of combat rolls.
• Be generous with your usage of any potions or scrolls you've found.  You can absolutely go through all of the game without ever using a single scroll and I only found I used potions in the first couple levels of the game.

This thread is missing the most vital key. Interesting, about the lights in the room - didn't know.

But the real key? Cantrip - Chill Touch. Prevents her regeneration and healing, making this fight WAY easier.

Broken Boards on the windows then i stood 3 members in between the windows and my fighter/pally on the stairs.

took out the minions that she leeches hp to replenish hers first.

Daylight spell, was doing damage, she did cast darkness but i moved my troops out of it to stay in the light

then basically tried to nuke her with everything the wiz could throw at her, she kept going my cleric who had a pretty decent ac with shield, think i had to long rest though had lvl drain on the cleric.

fighter had the two hander that does radiant damage, Pally was smacking with Smite and the punisher battleaxe and a board, rogue tearing up with a shortbow and in close the whiteburn ss backstab

keep thinking calm emotions as well stop frightened (cant remember) have to play it again

tough battle for sure

(played through twice)

Daylight spell, was doing damage, she did cast darkness but i moved my troops out of it to stay in the light

Just a nuance to avoid anyone getting confused : the spell Daylight does not cause damage to vampires (it is not really sunlight), or at least it was not the case during Early Access, and does not as per the written rules. BUT it should break the darkness spells and all dark areas and, if you break the windows open, real sunlight will enter the room and burn vampires and possibly penalize some creatures.

( From what I read, the spell Daylight does not seem to counter Darkness spells, which means it is broken as that is its technical purpose. i.e. I have not tested the released version yet.)

( From what I read, the spell Daylight does not seem to counter Darkness spells, which means it is broken as that is its technical purpose. i.e. I have not tested the released version yet.)

by RAW daylight can counter a 'darkness' spell of 3rd level or lower, however, there are other ways to get darkness besides spells and there are spells at the 4+ level that create darkness.  i don't know exactly what Aksha is using but just because daylight is not countering it does not mean the game is broken 

( From what I read, the spell Daylight does not seem to counter Darkness spells, which means it is broken as that is its technical purpose. i.e. I have not tested the released version yet.)

by RAW daylight can counter a 'darkness' spell of 3rd level or lower, however, there are other ways to get darkness besides spells and there are spells at the 4+ level that create darkness.  i don't know exactly what Aksha is using but just because daylight is not countering it does not mean the game is broken 

OK

Spirit Guardian was the key for me.

I talked her down at the start in dialog, then had my shadowcaster break open the windows with a cantrip. Turned her hostile ("you must think I was born yesterday") by making as if to steal from the armor dummy while in cautious mode, then immediately moved my party back up the stairs. Though now hostile, she was indeed born yesterday and did not immediately attack. I then lined up my party of four rogues (yup, four rogues: a shadowcaster, two thieves and a darkweaver) and initiated combat with a sneak attack from stealth, which gave us surprise. From there, we proceeded to burst her down most of the way before she was able to act, though she did use one legendary action to heal herself a little and another to try to attack my shadowcaster (but Shield said "no" to that). She did also manage to land a Slow on one of my thieves, so good for her I guess. Then we simply finished her off (using Cunning Action disengage where needed to ignore her minions and continue focusing her down), without having taken a single point of damage dealt by her.

The minions of course also rushed us, as noted, and we went to work on them next—the darkweaver and shadowcaster together on one and the two thieves on the other. So more sneak attacks all around, of course. One of them actually did manage to hit my darkweaver once, which Uncanny Dodge partly mitigated. Um ... yeah, that's about it. One of my party members actually got hit once.

All in all, that still made it tougher than most of our fights so far, as it's not uncommon for us to just wipe entire groups without being attacked once, much less hit.

Rogue master race.