Combat

[Dungeon Master]

Combat

Impossible To-Hit Numbers
Sometimes the attacker's to-hit number seems impossible to roll. An attack may be so difficult it requires a roll greater than 20 (on a 20-sided die!), or so ridiculously easy it can be made on a roll less than 1. In both cases, an attack roll is still required!
The reason is simple: With positive die roll modifiers (for magic, Strength, situation, or whatever), a number greater than 20 can be rolled. Likewise, die roll penalties can push the attack roll below 0.
No matter what number a character needs to hit, a roll of 20 is always considered a hit and a roll of 1 is always a miss, unless the DM rules otherwise. Under most circumstances, a natural 20 hits and a natural 1 misses, regardless of any modifiers applied to the die roll.
Thus, even if a character's chance to hit a monster is 23 and the character has a -3 penalty applied to the die roll, he might be able to score a hit--but only if the die roll is a 20 before any modifiers are applied. Likewise, a character able to hit a monster on a 3 or better, waving a sword +4, could still miss if a 1 is rolled on the die.
There are no sure things, good or bad, in the unpredictable chaos of combat situations.

Table 53:
CALCULATED THAC0S

Level
Group 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Priest 20 20 20 18 18 18 16 16 16 14 14 14 12 12 12 10 10 10 8 8
Rogue 20 20 19 19 18 18 17 17 16 16 15 15 14 14 13 13 12 12 11 11
Warrior 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
Wizard 20 20 20 19 19 19 18 18 18 17 17 17 16 16 16 15 15 15 14 14

Table 54:
THAC0 Advancement

Improvement Rate
Group Points/Level
Priest 2/3
Rogue 1/2
Warrior 1/1
Wizard 1/3


Calculating THAC0
To make an attack roll, the character's THAC0 must be known. This depends on the group and level, if the attacker is a player character or NPC, or the Hit Dice if the attacker is a monster or an animal. All 1st-level characters have THAC0s of 20, regardless of class.
For a character of level 1 through level 20, consult Table 53. This table lists the THAC0 number of each group through 20th level, so players don't have to perform any calculations.
For a character higher than 20th level, find the Improvement Rate for the character's group in Table 54. There you'll find the number of levels a character must advance to reduce his THAC0 by 1 (or more) points. Calculate the character's THAC0 according to his level.
The DMG contains the information on monster THAC0s.

[Dungeon Master]

What You Can Do in One Round

Whatever the precise length of a combat round, a character can accomplish only one basic action in that round, be it making an attack, casting a spell, drinking a potion, or tending to a fallen comrade. The basic action, however, may involve several lesser actions.
When making an attack, a character is likely to close with his opponent, circle for an opening, feint here, jab there, block a thrust, leap back, and perhaps finally make a telling blow. A spellcaster may fumble for his components, dodge an attacker, mentally review the steps of the spell, intone the spell, and then move to safety when it is all done. It has already been shown what drinking a potion might entail. All of these things might happen in a bit less than a minute or a bit more, but the standard is one minute and one action to the round.
Some examples of the actions a character can accomplish include the following:
Make an attack (make attack rolls up to the maximum number allowed the character class at a given level)
• Cast one spell (if the casting time is one round or less)
• Drink a potion
• Light a torch
• Use a magical item
• Move to the limit of his movement rate
• Attempt to open a stuck or secret door
• Bind a character's wounds
• Search a body
• Hammer in a spike
• Recover a dropped weapon

There are also actions that take a negligible amount of time, things the character does without affecting his ability to perform a more important task. Examples of these include the following:
• Shout warnings, brief instructions, or demands for surrender, but not conversations where a reply is expected.
• Change weapons by dropping one and drawing another.
• Drop excess equipment, such as backpacks, lanterns, or torches.

The Combat Sequence
In real life, combat is one of the closest things to pure anarchy. Each side is attempting to harm the other, essentially causing disorder and chaos. Thus, combats are filled with unknowns--unplanned events, failed attacks, lack of communication, and general confusion and uncertainty. However, to play a battle in the game, it is necessary to impose some order on the actions that occur. Within a combat round, there is a set series of steps that must be followed. These steps are:

1. The DM decides what actions the monsters or NPCs will take, including casting spells (if any).
2. The players indicate what their characters will do, including casting spells (if any).
3. Initiative is determined.
4. Attacks are made in order of initiative.

These steps are followed until the combat ends--either one side is defeated, surrenders, or runs away.
NPC/Monster Determination: In the first step, the DM secretly decides in general terms what each opponent will do--attack, flee, or cast a spell. He does not announce his decisions to the players. If a spell is to be cast, the DM picks the spell before the players announce their characters' actions.
Player Determination: Next, the players give a general indication of what their characters are planning to do. This does not have to be perfectly precise and can be changed somewhat, if the DM decides circumstances warrant.
If the characters are battling goblins, a player can say, "My fighter will attack" without having to announce which goblin he will strike. If the characters are battling a mixed group of goblins and ogres, the player has to state whether his character is attacking goblins or ogres.
Spells to be cast must also be announced at this time and cannot be changed once the initiative die is rolled.
Before moving on, the DM will make sure he has a clear idea of not only what the player characters are doing, but also what actions any hirelings and henchmen are taking. Once he has a clear view of everything that's likely to happen, the DM can overrule any announced action that violates the rules (or in the case of an NPC, is out of character).
He is not required to overrule an impossible action, but he can let a character attempt it anyway, knowing full well the character cannot succeed. It is not the DM's position to advise players on the best strategies, most intelligent actions, or optimum maneuvers for their characters.
Initiative: In the third step, dice are rolled to determine initiative, according to the rules for initiative (see "Initiative" below).
Resolution: In the last step, PCs, NPCs, and monsters make their attacks, spells occur, and any other actions are resolved according to the order of initiative.
The above sequence is not immutable. Indeed, some monsters violate the standard sequence, and some situations demand the application of common sense. In these cases the DM's word is final.