I'm shelfing this for a couple of weeks and check back on wikis to see if anyone put together builds that make sense.
Alright then.
Here are my characters and a guide to how I played them.
Savat (short for heavy metal band Savatage, I somehow forgot the last 3 letters)
the male Elf
Druid, later Druid Elder
Start with Primordial and Earth. Try to get Primordial to Expert as soon as possible to save cash (you can identify items yourself rather than having to pay 300 gold per item) so you can instead spend it on trainers and mana potions.
Earth is the best school of magic in the game in my opinion. Late-game Regeneration in combination with Elder Druid's Nurture will make most encounters a breeze simply because it will bring back any knocked out characters while always topping up the rest. Druids also have Stone Skin, granting the entire party armor equal to that of a plate mail. Early game, I found Remove Poison to be very useful as well.
My other school of choice was water, just to give him some offensive capabilities. In hindsight this doesn't really matter. You could stick to just Earth, because Earth also grants some decent damage-dealing stuff.
Get Mysticism up for some sweet mana, and use Magical Foci weapons.
You will spend most turns casting Regeneration.
I focused on Spirit first to get a better mana pool so that resting is more efficient and you won't have to mana pot as much. First few levels were all Spirit and perhaps a few points in Vitality. Druids have mysticism which increases mana on a percentage-basis, so I later transitioned out of Spirit and focused on Magic. My end-game attributes were 80 Magic, 45 Vitality, 45 Spirit. Rest were base values.
Garm (famous norwegian metal vocalist)
the male Orc
Barbarian, later Warmonger
This character could probably be replaced with any other class, as I never really found a good two-handed mace and he never really contributed much damage. His Challenge ability (aka taunt) from Warfare saved me a few times.
Very simple character. Just focus maces, two-handed, warfare and later endurance.
Stats in the end were 107 Might, 20 Perception, 45 Destiny, 45 Vitality.
Ilithia (who the fuck knows)
the female Elf
Blade dancer, later Blademaster
Main damage-dealer. You can probably go for daggers with similar result, but I never found any good daggers so I'm glad I went swords.
Swords, dual-wield, warfare and endurance were the main skills. I figured I wouldn't need dodge because I spend so much in Destiny for crit (which also grants evasion).
This character is actually more efficient with warfare abilities than the Barbarian because stuff will hit more often. I mostly just used auto-attacks. Blademaster's area-of-effect damage ability was rarely used as it cost too much mana.
Stats were 83 Might, 52 Destiny, 28 Vitality. I started pumping Destiny with a ratio of 1 might, 2 destiny, 1 vitality every level, then switched to just pumping up might and destiny and later just might.
The Blademaster's passive Cleave ability can be used to dispatch several low HP enemies in a single turn. This character really wrecks faces.
Dhurm (sounded dwarfish, I thought)
the male Dwarf
Runepriest, later Runelord
Early game, this is your primary damage-dealer. He will essentially solo the bosses and hard encounters of Act 1 while being healed by the druid. Blade dancer will surpass his damage output in mid-Act 2 or somewhere around then.
This character had two primary roles: Heavy damage crits with Firebolt, and Celestial shield. Celestial shield is very important for this party, and during challenging encounters this will actually be the Runepriest's primary function.
I GM'd Magical Focus and Fire Magic. I only had Light on expert level, even though Celestial shield was so important. Probably because I was focusing on fire damage output. In hindsight, I would max Light and Fire as primary skills. I also maxed (mastered) Mysticism for the mana.
Runelord's special active ability was a disappointment. The fire rune ability will hurt you more than the enemies. Perhaps it synergises better with another party, but not this one.
Stats were similar to the Druid's: 87 Magic, 40 Vitality, 40 Spirit. I also focused on Spirit first and later transitioned into Magic. Note that Dwarves get more HP per Vitality, so I intentionally let it slack behind up until mid-game.
A turn of combat with a more challenging encounter often went something like this:
Pre-buff resistances, if in combat only use if enemies are 2-3 grid away. When enemies are 1 grid away, cast Celestial shield with Runepriest, and if it's Boss or something similar, pre-cast Nourish (if you got Elder Druid – else pre-cast Regeneration).
First round cast poison cloud with druid, get armor debuff up with either fighter, cast Firebolt (or Fireball if it's a cluster of enemies) with Runepriest. If fire is resisted, tell your dwarf to fuck off and only use him for celestial shield for the rest of the fight (or perhaps see if offensive light spells work).
Second round, if Earth is highly skilled, cast the 50% armor reduction (acid splash?), else keep healing if needed. Rest just regularly attack (or taunt if needed) and cast fireball or whatever.
Repeat and refresh buffs. Keep Regeneration up at all time and remember it's not just a heal over time spell but also a direct party-wide heal so you can cast it for a burst heal as well.
This rotation with these characters will beat anything in the game on Warrior difficulty. The druid is by far the most vital character, with the blade dancer being the one actually killing stuff.
TL;DR:
Have a Druid with Earth and Mysticism, and a Blade dancer going for Swords and Dual wield. The two other characters can be whatever as long as you build the Druid to be a Regen/Nurture-spamming bot. (EDIT: oh an have Celestial armor on one of the other characters)