The combat mechanics are identical to those of Baldur’s Gate, which means that several counterintuitive and complex aspects from the D&D 2nd Edition rules remain. You can have up to six characters in the party, including your protagonist, and can directly control each of them if needed. Otherwise, you can assign a predetermined A.I. behaviour to any character you’re not controlling, so that they can take care of themselves in combat (if not, they won’t do anything unless you tell them to). E.g. the Ranged setting will make a character attack with any equipped ranged weapon and try to keep their distance from the enemies. You can toggle the A.I. on or off (helpful when you need to micromanage), and also select the entire party if you need everyone to move to the same location. You can also choose between several battle formations, which allows you to place ranged characters in the back and heavily armoured melee characters at the front, for example.
Combat takes place in real-time, and all enemies are visible on the map. If you have a Ranger, Thief or Monk, this allows you to scout and plan ahead for large groups or difficult enemies. Battles are subdivided into six-second ‘turns’, which are individual to each character (the countdown starts from the moment you select an action for that character). Depending on their class and weapon proficiency, a character can deliver a given amount of attacks per turn.
As far as stats are concerned, the game’s pen-and-paper ancestry means that everything is calculated on the basis of various-sided dice rolls (usually 20, but 4, 6, 8 and 10 are also used), from weapon damage to a character’s HP progression rate. It also means that some vocabulary such as ‘rolls’ or ‘Saving Throws’ is used. The latter are specific to each class and determine how well-protected a character is against Wand attacks, Spells, Poison/Paralysis/Death attacks and Breath attacks (i.e. dragons). The lower the number, the better. This also applies to a character’s Armour Class (AC) and THAC0. This means that an AC of 2 is better than an AC of 4, and that an AC of -3 is better than both. A piece of equipment may indicate “AC bonus +1”, but in effect, it will lower the character’s AC by one point when equipped. You also get AC bonuses if your character’s Dexterity is 15 or higher.
THAC0 means “To Hit Armour Class 0”. This is the number a character would have to ‘roll’ on a 20-sided die to hit an enemy, if that enemy’s Armour Class was 0. Basically, this determines a character’s accuracy. Again, the lower the better. So a THAC0 of -1 will be better than a THAC0 of 3. Confused yet? You also get THAC0 bonuses if your character’s Strength is 17 or higher. Additionally, for ranged weapons, a Dexterity of 16 or higher will grant another bonus to THAC0. Weapon proficiency determines three things: the number of attacks per turn, damage bonuses and THAC0 bonuses. The higher the proficiency, the more attacks the character will deliver, the more damage they’ll deal, and the lower their THAC0.
Most players will probably have an imported character, so their only concerns in terms of class will be picking a kit. For players that create characters from scratch or have a single-classed human protagonist, the most important thing to understand is dual- and multiclassing. A multiclassed character’s EXP is split between their two (or three) chosen classes. And while this means that they gain levels in both (or all three) classes at once, the process is also slower, and they will never reach as high a level as a single-class. They are also limited to either one or two proficiency points per weapon, depending on the class combination chosen, and can’t pick a kit for either of their classes. However, they always have abilities from both classes at their disposal, including High-Level Abilities or HLAs, as well as a better choice of equipment. In terms of HP, they gain half of what each class would get whenever it levels.
Dual-classing can yield impressive results. However, you have to know what you’re doing, and a) there will be a significant downtime phase, which doesn’t exist for multiclasses, and b) you’ll only have access to the HLAs of your second class. In order to start, the character must be level 2+ in one class and meet some attribute requirements: a 17 in the main attribute of the first class (e.g. Strength for a Fighter) and a 15 in the main attribute of the second…which, incidentally, means that Anomen isn’t allowed to be a Fighter/Cleric when you first encounter him, or if he fails his test. You can start as whichever class you prefer (typically, the one you need the least abilities from), as long as the overall result is a valid combination. Once dual-classing is triggered, the first class goes dormant, and EXP goes to the second class only. So, if the character started as a Fighter and duals as a Cleric, they will now behave as a level 1 Cleric. Once the level of the second class overtakes the first, the latter reactivates. It doesn’t gain any more experience, but complements the second class, within the limits of that class’ restrictions; e.g. a dual-classed Fighter/Thief can put five proficiency points into any weapon a Thief can use. The problem is that dual-classing too early is pointless (the benefits from the first class will be negligible), and dual-classing too late may leave you with an underlevelled second class. It’s a rather unforgiving system and, in my opinion, more of a hassle than anything. The other difference between dual- and multiclassing is that you can dual-class at any point, but you have to multiclass from the get-go. This also applies to the companions: you can choose to dual-class the human ones at any point if their class allows it.
Magic is subdivided into two types–Arcane and Divine–, and each type includes offensive, beneficial and indirect spells, designated by red, blue and white symbols, respectively. Divine magic is further subdivided into Clerical and Druidic, with slightly different spell selections. Arcane magic is used by Mages, Sorcerers and Bards, and Divine magic by Clerics, Paladins, Druids and Rangers. Paladins learn a smattering of Clerical spells, and Rangers some Druidic ones. Divine spells are learned automatically as the character gains levels and are not hampered by heavy armour. Some Divine spells can also be cast directly from scrolls, although it must still be done by a character whose class allows it. This notably concerns Lesser Restoration (which is the only way to quickly recover from Level Drain) and Raise Dead.
Arcane spells, on the other hand, may fail if the caster is wearing armour. The heavier the armour, the higher the chance of failure, so Mages and Sorcerers should stick to robes or elven chainmail. This may cause some grief to Mage multiclasses, until you can get your hands on some decent robes. Sorcerers learn their spells by gaining levels, while Mages and Bards need to scribe scrolls, which isn’t automatically successful. A Mage’s or Bard’s Intelligence determines not only how many spells s/he may learn, but also the likelihood of successfully scribing a scroll. That is distinctly more aggravating, because if the character fails the scribing, the scroll is still consumed. This unfortunately means that you should ideally save every time you plan to do some scribing, because, even if you feed the character some Potions of Genius–which temporarily boost their Intelligence–, there’s still a chance that a scribing will fail.
Since there’s no MP or mana, each spellcaster has access to several tiers of spells: seven for Divine spells, nine for Arcane ones. They can cast a certain number of spells per tier, which increases as they gain levels. Once they’ve exhausted their arsenal, they must rest in order to be able to cast again. Mages and Bards must also rest if they need to change their spell selection, in order to activate the newly-selected spells. This is a severely limiting system which forces spellcasters to be extremely conservative. So unless you want to rest between every battle, make sure they have some other means of attack for easy encounters. This is not a problem for divine spellcasters or Bards, but single-class Mages and Sorcerers have to rely on subpar ranged weapons most of the time. Which is both frustrating and counterintuitive: if I’m playing a caster class, I want to cast spells, not toss pebbles at the enemies! That being said, the game also features various wands. Each is infused with a different spell and allows a character to cast it a limited number of times. Anyone with a high enough Intelligence score may use them, but they’ll still be at their best in the hands of a Mage or a Sorcerer. Both Mages and Sorcerers can also cast spells directly from scrolls. This is more useful for Sorcerers, as they can thus have access to spells that aren’t part of their regular arsenal.
One more thing to watch out for is morale failure. If a character takes too much damage from a single hit, or if several other companions bite it, they’re liable to panic (their ground indicator will turn yellow) and start running around like a headless chicken. The only remedy is to wait until they snap out of it, but if there are traps or other groups of enemies nearby, this can quickly lead to trouble.