When starting the game first time and having searched Steam, Larian and other game forae beforehand you will find a lot of advice on character builds around min/max considerations. This is completely unnecessary. You CAN play and win the game with nearly any combination of hybrids as long as you give variety (in skills) some thoughts and look for characters/skillsets that complement each other. You CAN even win the final fight without any master skill (level 4 or higher), it just takes a bit longer. You CAN - easily - win any fight without being even near a maximum level in a particular ability (like strength or intelligence) with ease. All aforemenioned applies to all difficulty levels!

So instead of focusing on min/max builds let´s try to focus on very few key ingredients, which make the game more fun during game play, including (few!) spell mentions.

1) Character build considerations:

- Each first point in a new skilset delivers the best return on investment. Because you get 3 novice skills with small to moderate action point costs (your pool of available actions per combat turn per character). Without too much explanation, let´s look what a mage with just 1 point in every magic school would get: Hydro with freezing touch/ rain and regeneration (healing), air with blitz bolt/ teleportation and stunning touch, fire with burn my eyes (higher perception)/ wildfire (hastening) and flare (fire bolt), geomancer with spider summon/ midnight oil (oil surface which slows) and boulder bash (a kind of rock bolt), witchcraft with vampiric touch (drains life and transfers it to mage)/undead warrior summon and lower resistances (making enemies more susceptible to elemental spells). 5 ability points invested and you have 3 close combat spells (of which 2 potentially disable), 1 heal spell, 2 surface/environment change spells, 3 distance damage spells, 1 enemy removal spell and 2 support spells. All of these - after reaching intelligence 14 - might be used every turn. Note: It´s the touching spells that make battle mages particularly effective. I use this term for characters which are primarily fighters (in order to use man at armes skills and wear heavy armour) but have high enough intel to make spells useful.

- Speed is the second most important stat after the primary you decided on (like strength for warriors) as it not only increases available action points but increases your chance to move first. And who shoots first dies second (US marine motto). Except rangers, as for them perception (which increases only first turn action points) is more important than speed. Ah yes, you can of course go without perception and use summons instead, but weren´t we talking about fun? Having to constantly and repeatedly summon something while walking somewhere in order to not miss something important is not exactly my definition of fun.

- Disabling is more important than damage. Read that again three times. Easy as f*** - anything that can not act can not harm you. So you have more time for damage AND your own characters are safe. This is why speed - your available action points per turn - is sooo important. More action points - more possibilities to disable . You can have up to 7 enemies in a fight with your maximum 4 member party - wouldn´t it be nice to move first AND disable ALL in turn 1? And get your characters out of this fight without a single scratch?

- Immunities and chances defence against the aforementioned disabling effects are more important than raw defence or raw attack. So each point invested in willpower and body building are worth more than the same point invested in armour rating or weapon ability. And if the choice appears between wearing a ring that gives immunity to stun plus poison protection and a ring that increases you main fighting stats by 2 (like strength) plus delivers an even higher protection against fire: Choose the first one EVEN if you don´t need poison protection. Stun immunity is most important for your melee (if you use melee), as he can jump into an electrified water field which was (or will be) electrified by your own party. This clear prerogative for immunities means that while you acquire certain traits (main 2 characters only) during the game, always, always and always prefer those delivering immunities. In the final fight my 2 main characters are immune to: stun (ring), freeze (ring), charm (trait), fear (leadership AND trait), curse (trait). Note: Due to my experience there are exactly 2 fights during the course of the complete game where you might benefit from immunity to petrify, which also can be found on rings. But there are dozens where immunity to stun, freeze and especially charm (on higher difficulty) make all the difference.

- Leadership does more to boost your party abilities than any other investment whatsoever. Simply look at what each additional level of leadership (up to 6) delivers to 3 other members of your party.

- The character with the most leeway for secondary abilities (like bartering, charm etc.) is the ranger. This one only needs to invest points into exactly one skillset (marksman) and you even don´t have to get him to level 4 to be the most effective and versatile fighter of the party. So whichever additional abilities you think are fun - dump these on the ranger. If you strive to make your archer move first (you should), give him loremaster. With loremaster you can examine all enemies before the first shot to determine which attack will work best in addition to identifying magical equipment.

2) Fighting/Magic school considerations:

- The games initial 2 to 3 encounters seem to favour the earth/fire combination (e.g. midnight oil/flare). But looking at all encounters in the game combined the 2 more effective schools are air and water - the latter with the least amount of enemies with a decent or any defence against it.
- Most disabling spells come from air - with blitz bolt, thunderjump, stunning touch and headvice already 4 are available a skill level 2.
- Witchcraft is very, very, very important in the later stages of the game. Because with drain willpower/soulsap you can ensure that any status effect spell (like blitz bolt) works with a guarantee of very near 100%. And drain willpower is one of the 2 spells where no resistance is possible (the other one is teleportation). Basically the witchcrafters in your party set up the enemies for either themselvers or for another party member.
- Scoundrel is only important on the first level - for the winged feet and walk in shadows spell (see further down) and the pinpoint talent (grenades land exactly where you want them to land).

3) Ability considerations:

Having read somewhere else that you can do without bartering/ charisma/ /crafting/ blacksmithing/ telekinesis etc.? By relegating those abilities to non active team members or go without them? Yes, how rrrrright they are! But this is again not my perception of fun :-). Having to jump elsewhere any time you want something crafted, something identified? Not me. Having to manually repeat any rock/scissors/paper game because auto resolve loses each time due to low charisma? Not me. Having to wait quite some time in the game before being able to add some first level spells, thus fighting at a disadvantage in the first fights? Not me. So which ones make the whole game more fun to play?

- Loremaster, explained above
- Crafting. Essential for everything - from quick money to unlimited special arrows to boosted equipment
- Bartering. Lowers buy and boosts sell prices. Might be canceled (by re-spec) later in the game, when money is abundant
- Charisma. Again lowers buy and boosts sell prices plus vastly increases chance to win rock/paper/scissor games per auto resolve
- Telekinesis. Nearly crucial for a lot of tasks - from picking up filled barrels (not possible with low strength otherwise), gathering the scattered loot after a battle to risk free transfer of things (like keys) over dangerous surfaces. Once you get used to telekinesis 3 (good enough), gameplay without really feels exhausting. With 3 you can stand still somewhere and grab anything around in at least 10 Mtr. distance without moving
- Lucky charm. Not necessary, but definitely worth it. With characters having lucky charm numbers between 2 and 4 I estimate I found additional loot worth 50.000 to 100.000 coins in one playthrough, furthermore I always found some items which are very hard to find at vendors (e.g. rubies, which boost all elemental resistances on gear at once)

Unfortunately the nasty deeds section really is useless. Mostly because pickpocketing is limited (in value) and prone to costly failures, sneaking is made obsolete by walk in shadows, shadow essence boosts and invisibility portions and lockpicking is really a waste of points - what might be lockpicked could be destroyed as well, case closed.

4) Talent considerations:

Just a very few which are obvious if thought about.

- Pet Pal: Nearly crucial for first time players due to hints picked up from animals of all kinds (mostly rats). For game easiness should be on the party leader
- Demon: Powerful in its own right - allows for healing by fire and lava if you boost fire resistance to above 85 by other means. Most important for hybrid fighters as these can mindlessly jump even into burning oilfields
- Zombie: Powerful in its own right. Healing by the most common surface and most common combat threat of the game? Even more powerful in combination with Demon. Shoot your own fighter in the midst of enemies with poison clouds and explosive arrows and heal him at the same time :-)
- Pinpoint: 100 times more important than slingshot for grenade throwers. Grenades are very, very effective - but only if they hit what they should hit. Absolutely crucial for millimeter work directly adjacent to other party members
- Glass cannon: Out of experience I disagree with the conviction it´s not worth it. Yes, the 4 more action points per turn it delivers come at the hefty price of half the vitality (hit points). And? If the 4 more action points are used to disable enemies this is a non factor, furthermore additional hitpoint equipment loot is according my observation the most common in the game (at the final 21 level before boss fight my last glass cannon mage had more than 300 of his 800 hitpoints delivered by equipment). If you play it right (even in tactician mode) you will never ever experience an own character with less than 1/2 of its hitpoints at battle end. Never as never.

5) Attribute (stat) considerations:

You receive 15 attribute points during the course of the game up to level 21, the level you will most likely end up fighting the end game boss. 5 at creation, the other 10 at every second level up, on a base of 5 in each category. Due to my observation throughout the course of the game, it´s very easy to find or/and craft plenty of useful gear boosting the primary attribute (strength, intel, dexterity). It´s very easy to find plenty of useful gear to boost hitpoints either directly (plus x) or via additional constitution. It´s considerably harder to find gear boosting perception and especially speed.
Example for final fight - dual wielding battle mage: Has a base of 10 in strength, 10 in intel (1 from a talent), 8 in constitution, 8 in speed. 16 base points spent (15 + 1 from a talent). Wears 2 one handed weapons with a combined boost of a whooping 7 in strength, 4 in dexterity, one in leadership and 2 in speed (improved found/crafted gear). Wears one ring with 2 more in strength, 2 more in speed. Armour delivers another 2 in strength. A saron delivers 2 in intelligence. Ends with 21 strength, 12 intel, 8 constitution, 9 dexterity, 5 perception, 10 speed. Only for information - 23 is the last useful number for dexterity/intel/strength, everything above is wasted.
To put it short - found and crafted gear are what makes hybrid characters possible and effective, every combination is absolutely possible and playable (battle mage, battle ranger, mage ranger). Even a scoundrel absolutely works (not least due to the fact that special arrows don´t need any prerequisite and it is the only character with a benefit from the self crafted daggers with plus 3 speed after level 17), but makes some fights a lot harder, especially in the first half of the game.

Additionally you will in best case during the course of one playthrough find/buy or be gifted
- 3 books which deliver one free attribute point each
- 3 books which deliver 3 ability points each
- 1 book which deliver 1 intelligence point at the cost of minus 1 perception point

(TL/DR): On every difficulty in DOS EE any hybrid character works effectively as long as party composition is not too one sided. Some abilities are not strictly necessary but make the playthrough much more enjoyable like telekinesis. Min/max considerations are - given the battle difficulty - essentially a waste of time.