Rulebook: Combat Sequence

This one is very much a case of "it's not broke; don't fix it" - the rules are more or less the same as in 3e. The key things that differ are the ways in which surprise affects play (as discussed previously), and the removal of "flat-footed" from the game.

So...

The combat sequence is cyclic. Each combatant takes a turn in sequence, and can use his entire set of actions during his turn.

When Combat Begins

In most cases the beginning of combat should be obvious: the PCs encounter a band of orcs, the two sides draw weapons and rush to attack, and you roll initiative.

However, there are always the corner cases to consider. What if two characters are happily chatting away and one draws a dagger and stabs the other? As they approach one another, can one side prepare actions to spring on the other? And so forth.

Broadly speaking, combat begins the moment one character takes an action that the other side wishes to prevent. So, as soon as the player declares that he's going to draw his dagger, roll for initiative.

Further, until combat begins, the combat rules don't apply. As such, it is not possible for a character to ready an action outside of combat and thus short-circuit the initiative roll. Any such efforts are handled by the rules for surprise.

The Combat Sequence

The sequence for combat is as follows:

1. Determine whether one or both sides are surprised. If one side has advanced surprise, the other side misses all actions for the first round of combat.
2. All participants in the combat roll initiative, by rolling d20 and adding their Initiative modifier.
3. The character with the highest initiative result acts first, completing his full turn.
4. Repeat step 3 for each remaining combatant, until all characters have had a turn.
5. Complete any "end of round" book-keeping.
6. Repeat steps 3-5 each round, until the combat ends.

Determine Surprise

(See my previous post about surprise. I'm not going to repeat it here!)

Roll initiative

All characters roll initiative at the outset of the combat, even those who choose not to get involved immediately. Once the order of actions has been determined, the specific initiative scores can be ignored, as they will no longer be used.

Typically, summoned creatures, familiars, homonculi, cohorts, followers, and other associate characters do not roll initiative, but instead act on the initiative count of their host PC. In particular, should the host PC choose to delay his action, the associate characters also delay.

The DM may choose to roll initiative for each individual NPC, may choose to break the NPCs into groups and roll once for each group, or even roll once for all the NPCs. When rolling for groups, the DM will assign a leader to each group, and use that character's initiative modifier for the group. Members of a group can choose to act in any they wish, but must each complete their turn before the next can act.

End of Round

There may be a small amount of book-keeping required at the end of each round. For example, if reinforcements arrive after a number of rounds, this counter should be decremented here. If environmental conditions change, this will again occur at the end of the round.

At the end of each round, the DM should also quickly recap the current situation for all the players. Remember that the DM is the only conduit of information that the players have, and therefore it is better to over-communicate than under!

New Arrivals

Characters who come to the battle late always arrive at the end of a round. At this point, they should immediately roll Initiative, against a DC of 25 (Hard). If they pass, then they may act first in the round. If they fail, then the DM should place them about halfway through the initiative sequence, erring towards the end of the round. However, if the Initiative check is a natural 1, the new arrivals act last in the round.

If several groups arrive simultaneously, their individual initiative scores should determine their placement in the order relative to one another.

Example Combat Sequence

Two characters, Al and Bob, are fighting five orcs led by a drow. A second band of orcs are hidden on the battlefield, but will not act immediately. A third character, Charles, is racing to the scene, and will arrive in three rounds. And a third band of orcs will also arrive after three rounds.

At the outset of combat, the hidden orcs have surprise over the characters (but not the first band of orcs). Therefore, they gain advantage on the initiative roll.

Initiative is rolled. Al rolls a 17, while Bob rolls a 12.

The DM elects to roll once for each group of orcs, using the drow's Initiative modifier (+5) for the first band and a random orc's modifier for the second (+2). The dice for the first band comes up a '13', giving a total of 18, while the second band roll two dice (an '8' and a '20') and gain a total of 22.

Neither Charles nor the third band of orcs roll initiative; they will do so when they arrive.

The hidden orcs win initiative and so are entitled to act first. Additionally, because they possess surprise, they have advantage on any attack rolls against Al and Bob (but not the other orcs). However, they elect to remain hidden for now, taking no action.

The other band of orcs act next. They do not possess surprise, and so do not gain advantage on attacks.

Al acts next, and then Bob.

The round ends, and the DM decrements the counters for the arrival of Charles and the third band of orcs, and then recaps the situation for the players.

The second round proceeds in the same manner as the first. However, the hidden orcs do not now possess surprise; that moment has passed. They therefore do not automatically gain advantage on their attacks. However, they remain hidden, which may yet give them an advantage.

The third round proceeds in the same manner as the second.

At the end of the third round, both Charles and the third band of orcs arrives. Nobody is surprised - both Charles and the orcs were alerted by the sounds of combat, while being actively involved in combat precludes the others from surprise. Both groups of newcomers roll initiative. Charles scores a 26, while the orcs roll a 12.

In the fourth round, Charles acts first, followed by the hidden orcs, followed by the drop-led orcs, then the new orcs, then Al, and finally Bob.

The remaining rounds of combat proceed as above.