You are missing the beginning of chapter nine Dramatic Systems, which describes how to run the turns. This spans pages 399-401
During those action turns – especially the ones that cover combat situations – the Storyteller can break things down into three stages:
- Stage One: Initiative, in which the various players determine who acts in which order. (See below.)
- Stage Two: Action, during which everyone rolls dice and figures out what’s happening; and...
- Stage Three: Resolution, in which the results of those die rolls make themselves known. Damage gets figured. Success or failure plays out through character activities. And then the stage gets set for the next turn, where it all begins again.
For combat-based situations, see the section of that name. For non-combat situations, check Dramatic Feats, below. And for details about time, see the previous chapter.
It then talks about how to determine initiative. I will not quote the entire section just the gist of it:
- Initiative rating is equal Dexterity + Wits.
- Roll 1d10 and add initiative rating to get a number. Higher numbers go earlier.
- If two characters get the same number (e.g., roll of 3 + Dex 3 + Wits 4 = 10 and roll of 5 + Dex 2 + Wits 3 = 10), the higher initiative rating gets "wins" and acts first (Dex 3 + Withs 4).
- If the initiative rating is the same, both act and resolve their actions at the same time.
NB: The combat section does not explicitly state that players declare actions. However, surrounding text supports that interpretation. As does the legacy - since 20th Anniversary Edition is refinement of previous editions, then it does seem reasonable to pair that with the implicit mentions of declared actions in order to conclude that each character should have an action declared for them for each combat turn.
Continuing with the common sense interpretation, I will explain how things should work that fits the rules as written and as intended.
The initiative order applies for aborting actions the following way: combatants still need to say what they do and then the resolution happens later. Stage two and Stage three are distinct, as per the rules.
This means that the following situation happens:
Alice and Bob are in combat.
For simplicity, assume that the initiative order is first Alice, then Bob.
Bob decides to run up to Alice and punch her.*
Alice decides to shoot at Bob.
As Alice starts shooting, Bob decides to abort his planned action and dodge for cover instead.
In real terms, both characters decided how they wanted to act and Bob probably started to move towards Alice. After all, in real life, we do not move one by one during the same three second segment (combat turn), we act at the same time but somebody might just finish what they were doing faster. With that said, since Alice was quicker and opened fire Bob had to stop midway and dodge. That is what aborting a planned action is. Which is also why the Storyteller might require a Willpower roll or spending a temporary point. After all, Bob would not have just stood still.
Now, if we were to reverse the initiative order and made Bob act first - he would have moved and maybe attacked. When Alice opened fire, he would not have an action left, so he would not have been able to do a defensive manoeuvre.
To round up: remember that phase two of the combat turn (defense) only applies if a character is attacked. Therefore, if we introduce a new scenario where Alice, Bob, and Carol are all in a fight (assume alphabetical initiative order). Alice and Bob still take their actions from before:
- Alice is first and starts shooting at Bob
Phase 1: Alice has to roll to hit.
Phase 2: Bob decides to dodge which exhausts Bob's action but turns the attack roll of Alice into a contested one.
- Bob does not act further because he aborted his action.
- Carol has not had a chance to abort her action and can just execute whatever she had in mind at the beginning.
* It is worth pointing out that while 20th Anniversary Edition rules imply actions should be declared, they does not specify in what order order such declarations happen. In Mage: the Ascension Revised Edition includes this section which has a lot of practical sense:
Once initiative rolls have been made, each player (and the Storyteller) must declare what her character(s) are doing for the turn. At this time, it is also necessary to state if your character will perform multiple actions, cast magical Effects, use Willpower or Quintessence or perform any other strangeness. Players must declare their characters’ actions in the reverse order of initiative, so the character with the lowest (last) initiative number declares first, and the character with the highest (first) initiative declares last. Faster characters are thus allowed the opportunity to anticipate and react to the actions of slower characters.
It makes it much clearer how things work. A character with lower initiative declares their action first, so a character with a higher initiative can decide to react to that. If Bob had higher initiative order, he could choose to hide behind a nearby car, so Alice would have greater difficulty hitting or doing damage with her action. And if Alice has higher initiative, she might decide to devote her entire action to blocking without ever needing to spend or roll Willpower, since she is not aborting an action.
This also makes it clear when somebody would be aborting their action - after they have declared it but before they have acted.
The "reverse initiative order" declaration furthermore avoid another "common sense" problem. Initiative shows who is the "quickest" combatant in terms of reaction time. They are supposed to have an edge over the others. However, declaring actions in descending initiative order puts anybody with higher initiative at an disadvantage as they have to act blind. Conversely, anybody with a lower initiative is supposed to be having a harder time keeping up with the action, however, they get an advantage since they can base their actions on others'. This is definitely not how the rules were intended. From the description if initiative on page 399:
Those with high initiatives act first, while the others
scramble to catch up.