Bosses

Usually they appear at the end (or near the end at least) of each update. Some of them are alone and others have company. Usually they don't drop any kind of special loot or reward (except the experience of course).

=Plot Bosses=

Riala
Prologue

She is too much strong to be defeated at that point in the game (except by cheating), so the best advice it should not to spend any of your consumables in this fight, because you are meant to lose this fight.

Cache Guardian
It will spawn after Yarra joins the party. For your level, it's tough but you have a full party and is vulnerable and Lust attacks. Be aware that he can apply poison to whole party with Foul Blast.

Chimera
In the trail

It only use its most dangerous attack (Foul Blast) when its health falls below a certain level (at least in my experience). Even then and depending of the level of your characters it could be a menace, so don't pull your hits.

Lead Slaver
Meeting hall

Unremarkable in all the aspects. Providing that your entire party is in good health, you shouldn't have any kind of troubles with him.

Portal Demon
At the acedemy

It convokes more enemies as the fight progresses, but it's better to concentrate the attacks on it, before he has time to use more than once or twice its most devastating attack (the onslaught of Energy, an AoE spell that could kill all your party, except Simon).

Slaver Ringleader
Slaver warehouse

He has a good punch, but is vulnerable to the Poison Blade (you should have this skill by now). Also, he doesn't seem to have any kind of AoE. Beware that his minions using frequently the Heal spell (although not the Cure one so they could poisoned with immunity).

Seed of Corruption
Sineford's Mine

Not particularly difficult or powerful. Apparently it can't be poisoned but its loneliness helps. Doesn't seem to have any kind of special attack.

Ogre
Devil's Pass

Its AoE skill (Whirling Club) is not powerful against a rested party, but in otherwise it could generate some troubles but nothing unmanageable. Don't forget to loot the corpse near for a Dwarven Helm. The experience that you get is pretty nice too.

Noble Scion
Ari-Yhilina Palace

They key to win this fight is to eliminate the Scion first and then focus on a single wizard. They are tough customers, because they can heal themselves in one turn, so keep the pressure on them until their demise. Defeat the the scion using lust attacks (he is susceptible to Yarra's Sexual Torment attack). He drops a Shining Sword.

Unhuman
Desecrationist faction's house

He has a very poor agility, so will probably attack before/after Hilstara. Her Inhuman Aura magic attack affects to the whole party, but I hadn't seen any other AoE spells. He shares with the other Unmen their weakness against Lightning so a Level 21 Robin it's a formidable asset against him.

Varia's Second
Varia's Lair

This fight could be a cakewalk or something more challenging in function of the level and the composition of your party. If your Simon has already reached level 26, the possibility of using AoE skills like Simon's Commanding Presence, Yarra's Haze of Sex or Altina's elemental storms (some of them are weak against sex, some against fire) it will take care of all the minions in a couple of turns (three at most, if you decide to poison the Second at the start).

Stone Gargoyles
Old Fortress

A couple of tough gargoyles that attack when you try to access the basement. They have very high HP and are resistant to fire but they are weak against ice. They can be specially if your party is low in mana and/or health. They give more than 4000 XP so they are good to level up the party before the arrival of the Horde.

Aramite Elite
Eustrin

A tough Aramite Soldier, accompanied by four soldiers. As both Carina and Varia are relatively frail, it is recommended that you use Hilstara's Shieldwall and Carina's Shield of Purity. Among his attacks he can Blind or Silence a single target, so equip your party with the appropriate Pins. After that try to raise your defense and target first the normal soldiers. You get 3790 XP and 1052 Sx.

=Optional Bosses= These fights are not obligatory to advance the plot, but they are a pretty good source of XP and Sx or other goodies.

Heart of Horror
Devil's Pass Optional Dungeon

This is a tough bastard TM. It has no special resistances or weaknesses and it cannot be silenced, blinded, stunned or lusted (it can be poisoned but the odds are against it).

Some of his techs are: a single target damaged+paralyzed, a whole party damage+blind+silence, and a whole party damage+blind. It gives more than 3000 XP and comparatively few money (little more than 600 Sx). Defeating it, doesn't end the dungeon (so you still have time to eliminate any other enemy still alive).

Demonic Essence
Ari-Yhilina's Lower Town (Warehouse's basement)

You only find this boss if you had found the mysterious Cult. It has two companions with less HP and Mana. The boss has about 10000 HP and it has a dangerous AoE that really damages your party, but fortunately is vulnerable to poison. So the best strategy is to poison the three of them as quick as you can and to try to keep the three members of you party alive as many turns as you can. You'll get about 2300 Xp from this one, plus a pitiful of Sx and a great Robe.

Wards & Conducts
Ari-Yhilina's The Order of Yhilini Thaumaturgy

Once you had passed the three trials at the Order, you have the option to test a new Conducts test. It's a very challenging fight and the only reward is 2640 XP (and the admiration of its creator, that could help you in the long run).

The tactic described above was shared by Seil at the BKG forums.

As your party can be overrun easily, you have to prioritize the elimination of the enemies above doing general damage. Of the six enemies, conducts A and B are the least dangerous, so you give them less priority. On the other hand, Conducts C and D are, on the other hand, very dangerous but they are vulnerable to physical attacks so Aka could lead with then one by turn with Forceful Lunge. Meanwhile, both Robin and Altina should use Lightning attacks against the Water Ward (she is vulnerable to Lightning) and/or trying to keep the party alive. Once you have dealt with these three enemies, the rest should be doable (provided that the RNG doesn't kill you first: there is a element of luck in this fight).

Fallen Chosen
North-east of the succubi village near the Gathering complex

The following strategy has been proposed by Omega2501 in the blog. I (lostone2 speaking) still hadn't time to test it, but it sounds good.

Equipment: You should have some kind of lust preserver for both succubi and if you got the cache as one of your investments give Yarra the the charm of perversion (the yellow trinket) which gives her the Masturbate+ skill. Orcent should have the best gear that you can get with your available Sx.

Have Orcent spam his Defensive Attack or rotate two Defensive and one Piercing Attack. Qum should be healing always except if all the party is at top of HP. In that case, attack. Yarra will be either attacking or casting sexual torment most of the battle depending on if you made her more mage or more attacker just go with what does the most. Thats pretty much it the fight will take a bit, as he is resistant to your damage, so you don't do HEAPS to him keep your sp (the red bar) up for Yarra with the already mentioned Masturbate skill and you'll get there eventually.

=References=