How to communicate, in game, to a player that they are behaving sub-optimally in a specific section (that was designed for them)

Question

So, I have a PC (Barbarian) who is having trouble hitting things. Even with advantage. They are just not rolling well, and can't hit above a 11 on the dice.

The player has expressed some dissatisfaction with not having "a lot of options", even though with their build, it seems to me that they have 2 "levers" they can pull: Reckless Attack (Trading Advantage on Attacks Made vs Advantage on Attacks Made against you) and Great Weapon Master (-5 to attack, +10 damage). And this player always has both on. And they'd hit a lot of the time if they'd not use the GWM modifier.

So, I started adding some 4E-style minions to the game. Really low HP, standard AC, who this character can kill in one hit (even without GWM, they’re doing 3d6+8 on a hit, while raging). But they’re still constantly using GWM.

How can I communicate to this player (or any player), that their current SOP is not only sub-optimal, but is hurting their fun?

Answer 1

You need to talk to this player out of game

And when you do you have 2 topics:

1. Game mechanics, and their lack of understanding thereof
2. What options they are searching for, and why they feel they don't have any

Game mechanics

Your player clearly doesn't have a good understanding of chance to hit, hit points and all the other nuance involved in decision making when it comes to combat. You can't force people to learn, and as all teachers will tell you, even when you try and teach them you can't force them to care, or understand. But that doesn't mean you should not try.

Great Weapon Master in particular is a feat that isn't great when 'always on' because as you seem to understand it means you often miss, and also provides overkill in some situations.

I would explain to the player that fact, but honestly I would leave out the maths. The reason why is that I sense if the player cared about or understand maths well enough, they probably would notice it themselves.

Then demonstrate. Get the character sheet, roll some dice, and show them how in your latest combat they could have been creaming these minions. If you use an online dice roller you may even have all their historical rolls, so you can directly just show "if you didn't GWM here, you would have killed it".

Then continue to explain: A great weapon master which your character is by virtue of taking the feat, would understand this, and know when to use it. And then agree out of character, what in game clues you will give them to help make that decision.

For example, telling them how to recognise cannon fodder from a real target, how to recognise a target low on HP, how to recognise a target that will be too tough to hit with GWM, and conversely a target they are likely to hit.

This way you show the player why to make the decision, how, and then you help them carry it out.

However, you also need to talk about:

What options this player wants

Complaining about lack of options on a barbarian, GWM or not, is a problem they are likely to always have. Effectively they enter rage, and then swing an attack, maybe twice at the appropriate level.

There is little else, and that is just a fact.

Maybe they will be happy that understanding when to use GWM or not gives them enough options, but maybe they won't.

You need to get them to tell you what they mean by options, and then either explain that they do have those options, or agree that they don't and find a path to give those options.

It could be that D&D just isn't the game for your player, because in combat mechanically there are few options. Throwing sand in the opponents face, trying to grab them and tombstone them over your shoulder might sound cool, but mechanically aren't well supported and likely subobtimal - your player might be pining for such freedoms and other games (I am not the right person to say which) do offer those choices so might fit better.

Maybe your player is jealous of the wizard who gets to pick from an array of amazing spells, so changing characters is a good option.

You will have to talk to them and work this out.

But I would warn you, be careful what you offer them, because (and I mean this nicely) if you have a player who can't work out how to make a single decision on a barbarian they may REALLY struggle on a wizard or some other character.

Addendum

Buy your player new dice :)

Answer 2

Narrate the failure mode accordingly.

If the barbarian is missing attacks that would have hit but for the use of GWM, emphasize that in your narration of the missed attack, just as you would for things like the use of shield, resistances, vulnerabilities, etc:

Alright, roll for it.... 17, and with the penalty it's a 12, oh, that's a miss. Alright, you bring your weapon down, and while the skeleton isn't exactly quick on its feet, the extra wind-up time for your mighty blow is just barely enough to give it the split second it needs to slide sideways and out of the way of your strike...

Depending on your table's standards on attack narration, this can be subtle, or you could be more overt and directly cite the mechanics involved:

... If that had been a regular attack, without your GWM penalty, it would have been a hit.

If the use of GWM is overkill such that the extra damage goes to waste, you can narrate that on a hit as well:

The sheer power of your strike crushes the skeleton into a pile of bone splinters and dust under your weapon, absolutely obliterating it, covering you and everything within ten feet in a thin layer of bone dust, and leaving a wonderful little crater in the ground...

... It was frail enough that the attack was enough to destroy it even without GWM's bonus damage.

Answer 3

Talk to them outside of the game to understand why they are doing what they are doing. They may not be aware that what they do is to their disadvantage. Or they may feel that they invested in the feat, so they should use it.

In the latter case you can help them to explain that the option the feat is giving is what they bought, not the obligation to use the feat. (Especially if their complaint is that they have not enough options, this feat gives them a meaningful option to decide on every time they swing their weapon).

The nature of the GWM feat is such that it can be worse to use it than not if you need to roll a high number to hit. You could provide them with this table, so they can see the numerical effect they can expect. This will empower them to make the decision if they want to use the feat, based on what they see as opponents.

In the end however, it is their decision what they do.

Answer 4

In-Game

Narration

Describe enemies in a way that makes their strengths and weaknesses clear. As a player, I would understand the implications of something like, "You see the evil knight standing tall in the clearing. Her armour glistens in the moonlight from head to toe. In front of her stand four skinny, nervous-looking bandits, their tattered leathers looking flimsy in comparison. The bandit on the left still looks battered from his previous meeting with you."

If a strike misses because of GWM, narrate that the enemy managed to dodge during the moment that the player was gathering their strength. If they kill an enemy with much damage to spare, describe how the barbarian's axe cleaves right through the enemy. Stop Being Evil's answer includes some good examples, but you need to be careful that you describe GWM overkill (massive damage because the barbarian put all their strength into the blow) differently from critical hits (massive damage because the character got lucky with where the attack hit.

Use NPCs as Examples

Have the players meet an enemy barbarian or fighter that also uses GWM. Have the enemy use the "-5 for +10", or not, against the different PCs as appropriate. Even better if the party has some weak allies or summons of their own. Remember to narrate so it's obvious what is going on!

Out-of-Game

Check they Understand the Rules

The "-5 for +10" of Great Weapon Master can be chosen before the player makes each melee attack. Not only is it not always on or off, but they have Extra Attack, they can choose differently each time (unlike, say, Reckless Attack, which must apply to all attacks on a turn). So if they use it on their first attack, and they miss despite rolling 15, they know to take it off for their second.

Check their character sheet. At level 5, they should have about +7 to hit (+4 from Strength of ~18; +3 from proficiency). Subtracting 5 for a GWM attack still leaves +2, so they should be hitting AC12 if they roll 10 or higher. If they really do seem to always roll low, check exactly what they are rolling. It isn't impossible that they have confused the D20 with their D12 damage die; or that some macro on their Roll-20 character sheet is set up wrongly.

Check they Understand the Statistics

A -5 to their to-hit bonus is a 25 percentage point decrease. If they roll four attacks then, on average, one will miss that would have it if they hadn't used GWM (assuming the enemy AC is in a reasonable range). If they currently hit about a quarter of the time, using GWM on every attack, then they will double their success rate if they stop using it. Again, with technicalities that I'm not including natural 1s or 20s, and am assuming that the AC is reasonable.

Adressing their Complaint about Not Having Enough Options

Make Sure they Know all their Actions

While it is usually effective, a barbarian doesn't have to just attack on every single turn. Rage makes them very effective at grappling and shoving, because it gives advantage on Strength checks.

When you want to grab a creature or wrestle with it, you can use the Attack action to make a special melee attack, a grapple. If you're able to make multiple attacks with the Attack action, this attack replaces one of them. ... you try to seize the target by making a grapple check instead of an attack roll: a Strength (Athletics) check ... When you move, you can drag or carry the grappled creature with you, but your speed is halved ... (PHB, p. 195)

Using the Attack action, you can make a special melee attack to shove a creature, either to knock it prone or push it away from you. If you're able to make multiple attacks with the Attack action, this attack replaces one of them. ... Instead of making an attack roll, you make a Strength (Athletics) check ... (PHB, p. 195-196)

These are both explicitly melee attacks, even though they don't need an attack roll, so the barbarian can keep their rage.

This may seem underwhelming compared to 3d6+8 damage, but they allow some fun tactics in certain situations. Stop that mummy escaping from the Wizard's flaming sphere. Trip the assassin so that their target can run away. Shove enemies off cliffs!

Consider Allowing a Change of Sub-Class

What kind of barbarian are they? Some give more combat options than others. Totem Warrior (PHB, p. 50) and Zealot (XGtE, p. 11) give few extra options during each combat turn. But Berserker (PHB, p. 49-50) gives an extra attack each turn, and the ability to frighten enemies; Ancestral Guardian (XGtE, p. 9-10) gives a reaction to protect an ally; Storm Herald (XGtE, p. 10-11) gives an aura that can be repeatedly activated with a bonus action.

Some of these options might make combat more interesting for the player. There are no rules that allow a player to change their subclass, but it is reasonable for a DM to allow it in special circumstances. You could change it out-of-game (pretend they have always been the new subclass) or in-game (with the player's agreement perhaps a plot event makes the character so furious that they enter their first Berserker frenzy; or you could create a short side quest that helps the character get in touch with their ancestors, or be affected by elemental weather forces).