Does a charger's movement end when the charger's movement puts the charger adjacent to the target?

Question

In last week's Dungeons & Dragons 4e ersatz Sword Art Online campaign, the barbarian PC charged a target. When the barbarian's movement took him adjacent to the target of the charge, the target used a power that allowed it to shift when a foe of the target—like the barbarian—ended its movement adjacent to the target. After the target's movement, the barbarian wanted to use his remaining movement to continue his charge along a legal path toward the target.

After some wrangling, the DM ruled that the target's off-turn movement spoiled the barbarian's charge: the barbarian's movement essentially ended when the barbarian during his charge became adjacent to the target. Nonetheless, the group—all new to 4e—were unsure of this ruling's technical accuracy, the strictness of 4e combat making us all feel like this issue should be addressed by the rules somewhere, but we just didn't know where to look.

So, in sum, when a creature's movement during a charge puts the charger adjacent to a foe, is the charger's movement considered to have ended (even if the charger has movement remaining) therefore triggering effects like those above?

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Note: I apologize for not knowing the exact power that the target used, but the language really was something like When an opponent ends its movement adjacent to you, you can shift up to two squares. As a new 4e player, I apologize if this question doesn't use some game terms correctly. Further, as a new 4e player, a patient answer that explains this slowly is appreciated.

Answer 1

The wording of the trigger is the most relevant part of this. In your case, the triggering being specifically that the triggering creature ends its movement in a square adjacent, the movement portion of the charge needs to have resolved, and the power can negate the attack that follows the movement. Compare to the Assassin Utility 2 Smoke Bomb's trigger

Trigger: An enemy enters a square adjacent to you.

With Smoke Bomb, it happens immediately after they enter the square, as opposed to them ending their movement.

The difference that would be made with an interrupt would be the positioning of the enemy. If Smoke Bomb were an interrupt, it would happen while the monster was still a square away from you (so, for example, if another monster was basically a fighter that had you marked and the triggering monster was moving to flank you, at reaction speed the fighter monster's punish would have flanking, at interrupt it would not).

An additional note regarding Glazius' comment: an invalidated power may still be used depending on the wording of the power in question. A power like Hydra Charge (Fighter Encounter 7)

Special: When charging, you can use this power in place of a melee basic attack.

is determined at the end of the charge, while Iron Dragon Charge (Warlord Daily 9))

Effect: You charge and make the following attack in place of a melee basic attack.

is used at the beginning of the charge.

Answer 2

How to adjudicate this depends on what kind of trigger the monster uses.

When a creature has triggered actions in its action block, those actions are usually annotated with some type. You might see it as an immediate reaction, immediate interrupt, opportunity action, or free action. They also specify the triggering event or action, such as "another creature ends its move adjacent to you" or "another creature moves adjacent to you".

Yes, these are different triggers. The full breakdown goes as follows:

A charge is a single action with multiple "events".

Charge a Target

Action: standard action. [... F]ollow these steps.

1 - Move: The creature moves up to its speed toward the target. Each square of movement must bring the creature closer to the target, and the creature must end the move at least 2 squares away from its starting position.

2 - Attack: The creature either makes a melee basic attack against the target or uses bull rush against it.

Rules Compendium, p. 240

Any other power that says it can be used as a charge attack still follows these steps. The move ends before the attack happens, but for purposes of triggering enemy actions, the charge action is composed of several events.

Each square of movement during the charge is its own separate event.

Ending movement before you attack is an event.

Targeting the creature with an attack is an event.

Hitting or missing the attack is an event.

Dealing damage (if any) is an event.

Triggers all resolve differently.

From most to least restrictive... generally:

A creature can use an immediate reaction after the triggering action or event has completed. It can only use one immediate action before its turn comes up again.

A creature can use an immediate interrupt in response to an event, but the interrupt will resolve first; it can shield against an attack that would have hit it and the attack can then miss its boosted AC. It can only use one immediate action before its turn comes up again.

A creature can use an opportunity action with the same timing as an immediate interrupt, but it can take one opportunity action on each creature's turn.

A creature can use a free action with the same timing as an immediate interrupt. It can take any number of free actions on each creature's turn, but only one of them can be an attack.

Putting it all together...

A triggered action that reacts to "when another creature moves adjacent" is not reacting to the end of that movement, but rather the event of "moving adjacent" - one particular square of movement during the charge. The charge can continue if the charging creature has squares of movement left and can continue closing in.

A triggered action that reacts to "when another creature ends its move adjacent" is reacting to the event of the end of the move. The charge movement has already ended and cannot continue.

I can't claim to have access to all monster text, but I've looked through a few of my monster manuals. Monsters who have rules text about "ends its move" tend not to be using it in trigger text - they're skirmisher monsters who get a benefit from covering a lot of ground on their turn. Monsters that react to enemy movement tend to use "moves adjacent", like the level 1 Kobold Dragonshield.

Answer 3

The ability can only prevent the attack if it places the enemy far enough

Two things can end your move:

1. You run out of speed
2. You do something after which you cannot resume moving
   • Take a Standard or a Minor action
   • Fall prone
   • Attack, in case you were moving as part of a Charge

Rules Compendium changes the definition of Charge, compared to PHB. No mention of "ending your move" any more. Charge (Rules Compendium p240):

Move: The creature moves up to its speed toward the target. Each square of movement must bring the creature closer to the target, and the creature must end the move at least 2 squares away from its starting position.

As Glazius writes, "Each square of movement during the charge is its own separate event." So each square of movement can be reacted to.

The sequence of events:

1. Barbarian moves to adjacent square
2. The enemy has two options
   • Trigger the ability, then the Barbarian can chase if he has movement left, and attack it
   • Not trigger the ability, but then the Barbarian can attack it

So it can only help if this moves the enemy beyond the Barbarian's speed.
You can think of it as the Barbarian ending his move in each square he moves into, and then resuming it if needed.