This is just a short summary of the bosses within the Dungeon
Boss 1: Difficulty 4/5 (lots of aggro swapping)
Verosa, Lesch and Gurze
Three boss fight. Position your group at the boulder on the right hand side of the tanking area (its near an old weathered tree). Make sure that your group is all stacked as tightly as possible as it will prevent wipes and make the fight easier.
Pull Verosa to your party and tank her on the stack of players. Once she reaches 80% Lesch will become active and Verosa will become immune to all damage and inactive. No cleaves.
Lesch is the reason that your group is stacked, she does a crap-tonne of AOE damage that scales higher with further distance from her. Tanks make sure that you taunt Lesch as SOON AS she becomes active or she will two shot your healer. Once Lesch gets quite low Gurze will become active and Lesch will become inactive. No cleaves.
Gurze will slowly move closer to your party once he becomes active, taunt him just to be sure and RUN towards him, away from Lesch and Verosa which by now should be stacked on each other. Then face him away from your party and get your party to stack up behind him. This is because he has a frontal AOE cleave that hits quite hard.
Once Gurze gets quite low all the bosses will become active. Taunt Lesch just to be safe and pull her towards your group. Leave Verosa as she is useless. DPS Lesch first to shut down her AOE and keep your healers happy. Then Gurze and then finally Verosa. Verosa just attacks random players with a castable ability which is easily healed through.
Boss 2: Difficulty 1/5
Countess Surin Skenobar
Tank and spank, very easy.
She will randomly charge to everyone in your group and it does quite a bit of damage that is easily healed through. When she charges just sit still and let her do her thing. Seems to have a frontal cleave. When doing this boss spreading out seemed to work. Didn't play around or experiment with it much since it seemed to work.
Boss 3: Difficulty 2/5
Taunt Krasimir. Three waves of mobs will spawn. The first wave is 6-8 zombies, the second 3 zombie rogues and the third two zombie giants. Easily downed. Once the waves are killed head up towards Krasimir and start smacking on him. Tank him with your back to the altar so when he does his knock-back you only get popped into the air and not across the tanking zone. Casts a DoT that spreads to other players, easily fixed with dispell.
Boss 4: Difficulty 3-4/5
Destroy two wards that surround Vallnara's prison. Leave the last ward until you are ready to start the encounter. Once the ward is down she will become active and start to pat. Don't make the assumption that she wont attack until you do.
This fight is more catered to RDPS. Get your team to stand on the last ward platform together. Then pull Vallnara. Now this boss needs to be back peddle kited as she puts down AOE fields that do some nasty damage. I find that kiting her between the other ward platforms (not the one that your team is on) makes it easier and lets your team know where you are going. She has a frontal cleave I believe.
Throughout the fight Vallnara will charge one of your party and impregnate them (SPIDER VIOLATION!) this will put a debuff on the player that will spawn and add and do about half of their hp pool in damage. I'm pretty sure that healers can dispell the debuff to stop the add spawning.
It helps to have some tanky pets that can taunt the adds of your team or just pick them up as you kite past them. The fight is quite simple using this method but it can be troublesome if your dps isn't high enough and you wipe due to too many adds.
This is not a definitive guide and will most likely have mistakes and or miss information. Also note that this is for the low level FC (28-32)