Hmmm.......

I met very big resistance in some area from Hulks, Skeletons and Lich. (Bodhi labyrinth south east area)

Retread to evaluate the situation and decide what weapons to use because the traditional ones are ineffective.

Maybe the monsters have the protection and I have to use magical spells? Dunno.

How to kill damned Troll?
My commandos:
KMONSTER, Imoen, Minsc, Jaheira, Aerie and Korgan

Task: To kill some vampire Dace Sontan and take the Dace from its body.

Trolls only die if the deadly strike comes from fire or acid. You REALLY should read the manual, or at least on occasion read the loading text. It is written there as well >.>

As mentioned here previously, or in the manual, or in all walkthroughs, or the AD&D rulebooks, or ingame at Natalia's keep, or ampongst the loading-screen's tips: trolls must suffer fire or acid damage as killing blow, or they'll stand up with full health.

On monsters in general: stronger monsters are more and more magic-filled. This results, that they can be hurt only by more and more magical items. For example an Adamantium Golem can only be hurt by +3 weapons or higher. Some monsters even require +5 weapons!
Spells are another category, immunities against those comes like this: resistance/immunity to a certain element, OR immunity to certain level spells or below, OR very good saving throws in certain categories.
Also just to mention in ToB some monster can become immun to magic, so you can't harm them with any spell or any type of magical item (you must hit them with nonmagical weapons).
The last thing to know is monsters can be immun to certain type of damage, like Clay golems can only be hurt with blunt weapons.

A VERY USEFUL note for you: there is a smith in Baldur's Gate who can assemble VERY STRONG magical items from seemingly useless items (and some not so useless). You can bring all kind of shit and ask his opinion, or just check this list in a WT.

Never play games without patch enigmatic yoga ;)
And keep imoen! Treat your sister well!

A troll can be damaged with normal weapons until it falls down. Then you should stop attacking it (use the space bar for pausing and giving new commands) and switch to the next target while one character finishes it off with a fire or acid spell or weapon so it doesn't regenerate and attack again.
So use a weapon which does additional fire or acid damage, read the spell descriptions and memorize the fitting spells like burning hands, Melf's acid arrow, flame arrow, flame strike, fire seeds, conjure fire elemental, ...

Umber Hulks have a confusing gaze, so you might want to protect some party members with the level 5 cleric spell "chaotic commands" and use summons which don't get confused like undead.

Lichs can only be hurt by +4 weapons or better or high level spells. In BG2 summons are considered magical and can even hurt monsters which require +4 weapons, so a few hasted fire elementals or other powerful summons can work well.

Progress
 

Thank You, mates!
You are so kind as usual to stupid yoga.

Details:
Rats! I lost my spell case with about 20 non used spells. But I will not cry because:
Imoen - 32 spells memorized and 2 -3 times more known
Jaheira -28 spells memorized and 2 -3 times more known
Aerie - 31 spells memorized and 2 -3 times more known
-----------------
total - 91 spells memorized and about 200 spells known

Huge quantity, yes. Maybe I will find more.

The game
I have no words to express my feelings.
Nice, awesome game.
Maybe is better than Betrayer at Krondor. I dunno. BaK was my first love but BG2 is my last.. ha ha ha
No problem with sound and play run.
No one time freezing. Fast and stable.

@Scatty
Master, You're abs. correctly stating before .." this is beginning only"... Wow! Hard moments wait the brave everywhere. Even with these strong fighters, even with 3 healing magicians I am feeling very often helpless against enemies attacks.
@Capo
Si, Senior Capo.
Rodger that I will be very careful and protect my lovely sister always.
Between us only: Capo, I was really very near to do fatal mistake. Yes, there was a moment when the brave wants to say-- I love you, my dear..?! Can You imagine??
But, gladly I understand that this is my sister and did not make that fatal fail.
@Hungary
Yes, yes, I know that the stupid does not read the WT, that he is lazy beggar and so on.
But some of my friends ask me - The brave, why you use WT? This fact reduces the game charisma.
More over I do not want to know that after the first corner will wait me the monster named Twillight, and after the second - the next monster named Hunvagy.
Surprise is a main factor of game for the brave.
Twillight, I visited that Smith in question but he explain me that he needs a special stuff I do not posses.
@Kmonster
Yes, the trolls were dead after I used fire weapons when they down on the ground.
I used the spell Summon Monsters against Skeleton Warriors and the spell Aerial Servant against Lichs.
Hmm.. still I do not enter fight with Hulks. I do not like to fight when the doors fall down behind me. Maybe in a good time will enter their mazes.

My location:
Island Brynnlaw
Spellhold
The Apparition test me with some riddles.

I SAID MANUAL NOT WALKTHROUGH. Which includes a goddamned bestiary, that at least vaguely describes each new critter you might meet and how you best fight it. It is considered common knowledge by your characters and by the player. This is not fucking Diablo, where the monster carries a 2m by 3m sign "OHAI I'M IMMUNE TO POISON ASSHOLE".

Here's the Complete AD&D2 Monster Manual, use it.

:)

Please, need I from:
Accorns
Genie's flack
Sh.Thief cellar key
Gogged man
Jar of water
Air elemental statue
Wooden stake - 3 pcs (More vampires to eliminate?)
Hourglass
Mirror
Yoshimo hearth
Kurtulmak Crystal shard
Mind flayer painting
Mithril token
Hand of Dace
Giant troll head
Griming skull
Golden circlet
Warden's note ...Heed this, inmate. The true test of madness is...

TY