Grimrock

Damage damage DAMAGE. Fire has been left to do what fire does best. Kill things. New burst spells, cone, square and line AOE Besides killing things, we have a couple of buff/enchamtments, a mage light spell and also Enhancing Flames - which is able to turn (27 different) items into other better, more fire oriented items (eg Longsword >> Tempered Longsword)
Fire magic has spells upgraded by Fire, Air and Spellcraft. Some fire spells are also amplified by certain runewands

Ice magic will always have the strategic advantage of freezing things - especially with the freezing burst spell. As such, ice does lags behind other skills as far as raw damage goes (more skill required to learn AOE damage spells for example). However, ice magic now boasts many buffs and enchantments - Regeneration, Vitalize, Standardize and Preservation for example... Ice magic also holds one of the most usefull utility spells - Extinguish - which dominates fire based enemies and can remove different types of blockers and damage fields. Ice magic is also one of the few skills to possess a ressurection type spell, as well as other healing magics.
Ice magic has spells upgraded by Ice, Air, Fire, Earth and Spellcraft. Some ice spells are also amplified by certain runewands

Air receives an interesting mix in Labyrinth of Lies. Air magic still rivals fire as far as damage dealing goes, but also now has many utility, evasion, protection and access spells. Blink, Repulse (push monster), missile shield, Invisibility, deflect missile and Force Field all provide evasion and protection..... While Wisp Shift allows access to exclusive secret areas and Blink Gate provides the only means to access one of the secret levels - The Aetherlands. Further, air magic possess another powerful utilty spell - Electrostatic Pulse - neutralizing energy based enemies and removing many blockers and damage fields. All in all, air magic is packed full of fun!!
Air magic has spells upgraded by Air magic and Staff defense. Some air spells are also amplified by certain runewands

Earth magic I have been very generous with - as I felt it didnt stand up to the other skills in the original game. Earth magic still deals with posions (Vapor Snare, Deadly Vapors, Cure poison etc) but also now utilises many rock/metal projectiles (Blades, Whipping Rocks and Venomstone Shot for example) - dealing physical damage to get around monster immunities. Worried about starving, no dramas - Unchecked growth and Create Food will see you through. Plus, earth has protection magics to keep your champs alive in intense battles. Earth also uses a heavy duty utility spell - Deconstruct - annihilating mechanical monsters and removing cave ins and huge boulders effectively. Like fire's enhancing flames, earth magic is given the ability to Transmute (31 different) items and ammo into other other items!! Most importantly though, Geomancers have access to the Gaia Gateway spell - the only means to access one of the secret levels - Yggddrassil.
Earth magic has spells upgraded by Earth and Fire magic. Some earth spells are also amplified by certain runewands

As the story goes, The Watchers have broken the divide between Light and Dark magic - they now intermingle and are grouped together under spellcraft. Life and Death magic it is!! New burst spells (eg, Darkburst), projectile spells (Light/Arcane Missile and Dark/Dread Missile), item manipulation spells (eg, Enchant Dark Arrow and another enhancing flames type spell - Necrochemy) and Healing magics too (Healing Light, Cleansing Light, Life Steal and Ressurect). Spellcraft also dabbles in a bit of "blood" magic, using party health to deal damage or restore energy.... Undead monsters will cower before you with offensive spells like Smite Undead and Banish. Importantly, spellcraft possesses Dark Vortex, which when cast at certain altars through the game (or back through the game rather) will take you to the secret level - The Shadowlight Divide.
Spellcraft spells are upgraded only by spellcraft. Some spellcraft spells are also amplified by certain runewands

The magic skill of the Battlemage!! I felt staff defense suffered a lot in the original game so it has received the most attention! There are a variety of utility, buffing, detection and offensive spells. Enchanted Might, Stave Shielding, Resist Magic and Absorb Magic help the party survive rough fights..... Magic Arrow, Prismic Missile and the very very versatile Prismic Assault provide the raw damage.... Detect Monsters, Detect Secrets and Detect Traps will keep you prepared for fights and finding hidden loot..... Prismic Prison, Calm Monster and Silence will hamper monster advances.... while Recharge Item and Syphon Item allow for some interesting wand charge tricks. Staves also boasts the Portal spell - allowing the party quick jumps back and forth through out the Labyrinth later in the game. Importantly, one Staff Defense spell, cast along side an Ice Magic spell (with a little help from a certain potion ingedient) will send the party off to The Dreamfields, the last of the four secret levels.
Staff defense spells are upgraded only by staff defense. Some staff defense spells are also amplified by certain runewands

On the first floor, that is the third level of the dugeon, there's a room with an ogre. My party is strong enough to kill it with a couple of hits, then I got stuck in the room, since he was not there anymore to open the teleporter or the main door. The only solution I found was spawn another ogre in the room with the console, or teleport using the console again. Is that it, or I missed something?

I had not anticipated people being able to kill that Ogre, but obviously with an imported high level party it is indeed very possible.
The intended way for the puzzle to work (with a low level party that cant kill Ogres yet) is get the Ogre to step on a plate, time you escape through the portal without getting hit.
This takes you back to the fireball corridors... you can then lure the ogre into the fireballs.... OR.... lure it into the area with the spiders (after killing the spiders),
running back out and shutting the portcullis at the entrance to that area

there's a room with two alcoves blocjed by pillars, can't access the itens. It's just a bait to drive us mad?
But the real problem is the kind of lord of the rings door on the floor 4. Guess I made all he stuff needed on the three rooms you can acess, the one I mentioned above (got a secret there,btw), the one with "do not distube the red gem" and even the hardest "gems and rocks will not help you here, you have to jump across little insects". In this room I found a secret button thet when pressed says I hear sound behind me, but I could not see anything different opened.

You will/should find 2 pieces of Ore (machine part north) - one behind some spider eggs on level 5 (accessed from "gems and rocks will not help you here, you have to jump across little insects" room) and one in a chest at the teleporter/gate puzzle after the spider area in the east of level level 4. Now next to the room with the middle pillars blocking the items, there will be 2 receptors. You need to place the ores in the receptors to open the LotR door (door of durin) - This will allow you to progress with the rest of the level and will also remove some the middle pillars blocking the items in the nearby room...., the other secret I assume you mean from that room is from the lever puzzle?? - finding potion recipes and a wooden box with bonecraft supplies. Also, with the teleporter/gate puzzle after the spider area, there are 2 secrets with chests - find both small secret buttons! The clue "All teleporters lead you back to the same place" is obviously a BIG LIE. At some positions the teleporters take you to other places in the room and that is how you navigate that puzzle. The secret with the hud Print text about hearing something behind you that you mentioned... actually closes a pit back out in the middle of that main cavern area... leading you to the seemingly in-accessable chest (and some tentacles) in the middle of the room. Do you think in game I left adequate explanation for the ore - receptor - door of durin puzzle?? Im thinking I have not made it clear in game.... thoughts??

Ok, "You left it behind, didnt you?" is referring to the red gem.
You will find when the clue is talking ambiguously about "it" or an unnamed object - it is a gem you need.
You should still have the red gem with you (but you may have left it behind in the puzzle on level 4)
Further into level 6 you will come across 2 blue gems and a green gem (and a replacement red gem too)
You need these in the next 3 levels to progress
The wisp shift positioning is a big mistake... the area with the shrakk torr bees (wasps) is part of the Grand Staircase which you do not (should not be able) to access until the end of the game. My mistake with the wisp portal positioning.