One of the benefits of the Great Weapon Master feat is:
On your turn, when you score a critical hit with a melee weapon or reduce a creature to 0 hit points with one, you can make one melee weapon attack as a bonus action.
If I have movement left after dropping an enemy with this feat, can I move to another enemy out of melee range and use the bonus action attack against them?
I know the Extra Attack class feature allows moving between attacks, but I'm unsure about this case.
On your turn, when you score a critical hit with a melee weapon or reduce a creature to 0 hit points with one, you can make one melee weapon attack as a bonus action.
The phrasing here says nothing about the precise timing of the bonus action. It can be simply read as saying that after the condition is met (critical hit or reducing to 0 hp) that you are granted the ability to make a bonus action attack. It never says the bonus action must be taken "immediately" or anything along those lines so the timing of the bonus action attack is not restricted at all.
You choose when to take a bonus action during your turn, unless the bonus action’s timing is specified
The rules for when you can take a bonus action say that if the timing is not specified, then you can choose when to take it. Thus, there is no reason why you would not be able to choose to move before taking the bonus action attack.
If you take an action that includes more than one weapon attack, you can break up your movement even further by moving between those attacks. (PHB 190)
Even within a single Attack Action, the rules allow one to move between attacks. It absolutely makes sense that they would allow it between an Attack and a bonus action attack for example. After all, even if the bonus action isn't considered to be part of the Attack action (or whatever triggered the GWM bonus attack condition), it is indeed a weapon attack and thus moving between them seems like an incredibly reasonable interpretation.
Jeremy Crawford has clarified this exact issue via Twitter and agrees with the interpretation above:
The intent is that you could move before taking the bonus action in the Great Weapon Master feat.
Yes, it is unclear but we can look at similar uses of the word "when" here:
Two-weapon Fighting
When you take the Attack Action and attack with a light melee weapon that you're holding in one hand, you can use a bonus action to attack with another light melee weapon...
The consensus at my table is that the Bonus Action attack from Two-weapon fighting can be taken after moving. Similarly, the Great Weapon Master feat Bonus Action can also be taken after moving.
After running it this way, I have found that the GWM users have had a significant edge over the rest of the party (3 of 8 players took the feat) but it's not because of the bonus attack, it's because of the amazing +10 damage; the Bonus Action attack is merely icing on the cake.
Given that the default scenario with multiple attacks is that you can split your movement and attacks up however you like, I'd assume that an attack granted by a bonus action doesn't differ in that regard.
In general, you can move during attacks:
Moving between Attacks
If you take an action that includes more than one weapon attack, you can break up your movement even further by moving between those attacks. For example, a fighter who can make two attacks with the Extra Attack feature and who has a speed of 25 feet could move 10 feet, make an attack, move 15 feet, and then attack again. (PHB p 190)
This particular extra attack is a bonus action:
You choose when to take a bonus action during your turn, unless the bonus action’s timing is specified
So I guess the question is whether the timing is specified by the feat? It certainly sounds like it:
when you score a critical hit with a melee weapon or reduce a creature to 0 hit points with one
I'd interpret this to mean you must take the bonus action right after the attack hits. That's pretty consistent with its interpretation as a cleave like effect.
I haven't played much 5e yet, but I don't think it would be unbalancing to allow you to take it after moving, especially if it makes narrative sense. The restriction of one bonus action per turn is the balancing factor, and there seem to be lots of ways to use it for an attack.
When fighting in melees, for real, the experience is that you carry your attack THROUGH your opponent into the next opponent within reach. You do not move any more than a shifting of your stance in order to retain your balance
Butchers use cleavers to cut all the way through a joint of meat. Their blow will usually go all the way through the joint into the chopping board below. The expression used is that "the butcher cleaved right through the meat and into the chopping board". What statement is used to describe the butcher cleaving through the meat and into the meat on the table 10 feet away? The whole idea is ludicrous. It is a bonus action because it carries on from the initial action without the need for a completely new determined action.
I think a bonus action can best be described as an instinctive action. You do bonus actions because they happen at the right time in the right circumstances not because of planning.
It is similar to a left or right handed child. They will always use their primary hand to write and do most actions. An ambidextrous child has to think which hand to use to write. We have problems with the direction we write. More often we write forward with the right hand and backward with the left hand. This has led to, in the past, the ambidextrous being forced to use only their right hand, to write, by hitting the left hand or restraining it in some way. Using the right hand becomes programmed and continues for years afterwards without thinking.
It becomes instinctive to hit the next target over when your blade has the momentum and is heading in the right direction. It is part of the training for the feat. Don't waste the momentum. That momentum will not survive you moving 10 feet, unless you act like a spinning top and turn in circles.
With pure logic, if you hit your primary opponent with a blow following a path from left to right then you should not have a bonus attack against a secondary target standing to your left. You will need to stop the weapons momentum moving right and reverse it to swing to the left. If you struck the blow from right to left then your secondary target, being on your left, is in line with your momentum and direction. Thus a secondary bonus hit is available with only minor changes in the swing (ie sweep up or sweep down) the momentum carries on in the correct direction.
As it is a reaction i would imagine not, the extra attack class feature grants you another attack in your progression, Just like a spell that has a casting time of reaction, i interpret this to act that way, and unless hasted i would say it is where you are standing.
