Baldur’s Gate is basically a standard dnd war chess battle, with all characters acting in the order of initiative (through d20 + agility adjustment + other initiative influences).
In a surprise attack, if you fail the Perception check, you will be surprised. You will not be able to take actions in the first round (also generally called the surprise round).
Therefore, the more crucial the battle is, the more opportunities there are to arrange your position covertly, and try to launch a surprise attack to surround/cut off/get close to the enemy.
Characters that can act can perform movement, standard actions, bonus actions, and reaction actions each turn, and basically each action can only be performed once.
Standard Actions: Standard actions are actions that can be performed once during one’s turn. They are often large and time-consuming abilities, such as casting a spell or making an attack. Standard actions can also be used for throwing, sprinting, stupefying strikes (stunning), and assisting.
Bonus Action: A bonus action is an action that can be performed once during your turn. It is usually a quick action or ability. For example, a quick spell or an off-hand attack. Bonus actions can also be used for jumping (evacuating), dipping, pushing, and hiding.
Reaction: A reaction is an action that can be performed on any turn. It is a response that you trigger when a condition is met. But when you perform a reaction, you can’t use it again until the beginning of your next turn. The most common reaction is an opportunity attack triggered when an enemy leaves your attack range.
Here again, let me emphasize opportunity attacks:
The range of 5 feet (which you can consider as close range) around each character is its control range. As long as a hostile character leaves (note that it does not enter) this range, an opportunity attack will be triggered.
Therefore, when the opponent you are entangled with wants to leave, or he wants to pass you to hit the teammate behind you (who approaches you and then leaves), it will provoke an opportunity attack.
An attack of opportunity causes you to automatically attack him once, with advantage on this attack (whichever is higher).
Therefore, the basic strategy of the battle is to use tanks/highly mobile melee characters (usually more resistant to attacks) to block important roads or high-threat targets (especially ranged ones) close to the opponent to prevent the enemy from attacking your vulnerable characters.
Let your firepower take out high-threat targets.
Even if the enemy wants to break free, it has to pay the price of spells/actions or suffer attacks of opportunity.
There is another advantage to getting close to high-threat enemy targets, as these targets often deal mostly long-range damage.
Ranged damage (whether bows or spells) is at a disadvantage when there are enemies in close range, and the hit dice are the smaller of the two dice.
Such entanglement will force the opponent to make a choice between delaying the attack (using an action to get rid of the entanglement) or accepting an opportunity attack (leaving), gaining an advantage on the battlefield for you.
Some spells also use reactions.
Expend a spell slot to cast the spell (without consuming any actions) to trigger the reaction the next time the conditions are met.
For example, spell counterspell can react when the opponent is casting a spell, causing the spell to fail. It is also a powerful control interruption and is very important.
When attacking with a weapon, you can hit the opponent if the roll of d20 (20-sided dice) + Strength/Dexterity modifier + Proficiency bonus ≥ the target’s Armor Class (AC).
Depending on the weapon, weapon attack hits are based on Strength/Dexterity. Most melee weapons are based on Strength, while ranged weapons are based on Dexterity, or if the melee weapon has the Dexterity modifier. Note that when using a melee weapon with the Dexterity modifier, the higher of your Strength or Dexterity is used to determine the hits. Some classes allow you to use other modifiers to determine the hits with weapon attacks. If you are using a weapon with proficiency, you can also add your proficiency bonus.
The hit rate of a spell attack depends on your primary attribute for spellcasting. (The primary attribute for spellcasting is different for each profession, see the profession and spell description, for example, the primary attribute for a mage is intelligence, the primary attribute for a priest is perception, and the primary attribute for a warlock is charm.) If your primary attribute for spellcasting is intelligence, then whether your spell attack hits or not is based on your intelligence. Moreover, as long as you can cast spells, your spell attack hits will definitely give you a proficiency bonus. The formula for a spell attack hit is: d20 + spellcasting primary attribute adjustment value + proficiency bonus. If your attack roll + various adjustment values are greater than or equal to the enemy’s armor class (AC), then the attack hits!
Regardless of weapon or spell, if your d20 rolls a 20, it means your attack will hit directly and cause a critical hit (the damage dice is doubled, see below)!
If the d20 rolls a 1, it is a miss.
In general, weapon and spell attacks can be divided into ranged and melee, but in most cases the way they calculate hits is the same, and more often than not some specialties/abilities can only work on melee/ranged attacks.
Armor Class (AC) is also an important existence in DND. Depending on the type of armor you wear, the calculation method of armor will be different. At the same time, the base armor of a creature is generally 10.
No Armor: Base Armor (10) + Agility modifier
Light Armor: Light Armor Value + Agility Modifier
Medium Armor: Medium Armor + Agility Adjustment (up to +2)
Heavy Armor: Heavy Armor Armor Value
You often have a hit advantage against enemies in uncontrolled states such as lying down, dizzy, etc. The advantage can also gain you an opportunity attack or damage advantage.
Therefore, when fighting, try to put the strong enemy into this kind of unfavorable situation.