How can I play a supportive-style Polearm Master Fighter?

Question

This is a follow up to this question. I will start with the party context: We are playing Princes of the Apocalypse in a huge party, composed of: Tiefling Sorcerer, Human Dual-Wielder Ranger, High Elf Rogue, Dragonborn Paladin, Half-Elf Warlock, Dwarf Cleric, Half-elf Monk and me, Human Fighter.

My current build is a Variant Human with Polearm Master and Glaive, going for Battle Master, plus Sentinel and GWM as feats later on (by later on I mean I'll have both at 6). As mentioned by Korvin in the other question, this is a high DPR build, but I do intend to play it in a supportive manner. How exactly can I do that?

My ideas up to now were: Shoving (instead of just attacking) so our Ranger gets advantage (gets better with Trip Attack), zoning with Reach + Polearm Master (better when I get Sentinel) so I can protect our squishies, and I do intend to go for Commander Strike, although not DPR-optimal, just to make them attack more often and feel good about doing damage.

Still, our Rogue has talked to me saying he feels a little useless, and our Ranger is mainly focused on DPR and I don't want to overshadow him by just doing a massively higher amount of damage. I could help them optimize (and probably will), but in the meantime, (how) can I play this Fighter build in a more supportive way that makes my fellow companions feel better about their own characters? My main concern is about these two dudes, the Ranger and the Rogue have been focused in DPR and another massive DPR character (that will probably out-DPR them unless I help them optimizing) would overlap too much into "their thing".

On a second thought I should probably have built this differently, although my preferred Support Fighter build (Grappler) would suck in our setting, since with 8 players in the table, the DM is throwing mobpacks at us. Either way, I like the build, so I would prefer to keep it and see if there's something I can do about the "helping others" aspect.

Note that we are limited to PHB, and possibly no multi-classing, although I still have to ask my DM about that.

Answer 1

Buff the rogue with Commander's strike

Sneak attack:

Once per turn, you can deal an extra 1d6 damage to one creature you hit with an Attack if you have advantage on the Attack roll

Commander's strike:

When you take the Attack action on your turn, you can forgo one of your attacks and use a bonus action to direct one of your companions to strike. When you do so, choose a friendly creature who can see or hear you and expend one superiority die. That creature can immediately use its reaction to make one weapon attack, adding the superiority die to the attack's damage roll.

Since a rogue can use Sneak attack once per turn and not once per round, the rogue can sneak attack both on her own turn and on your turn, and do significantly higher damage.

Answer 2

Focus on what you, uniquely, can provide for your team

As a Polearm-focused fighter, you will never be in a position where you have an abundance of support abilities.

But there are still a few.

Rather than focusing on how to directly make your teammates stand out, you can instead focus on things that only you are capable of doing. Your Rogue and Ranger will have excellent stealth actions, damage, and ranged attacks. Your Cleric will be able to shine while supporting your team with healing and Concentration spells.

But what do you do that nobody else can? If you focus on that, you can ensure that you're supporting your team in the way that only you can, so that you both cover an explicit weakness to the party as well as not stepping on their toes in usefulness.

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Investments

You can grab that Great Weapon Master feat, but that will not accomplish your goal of making your teammates shine. Rather, you'll likely steal a lot of the glory by dealing loads of damage. Damage is always important, but considering that is already available to most of your team, let's see what some other options are:

• Mage Slayer feat. Works exceptionally well with Polearm Master, and it helps keep your teammates safe from dangerous mages.
• Sentinel feat. THE tanking feat, this will keep enemies from approaching your allies and allow you to deal extra damage when you're ignored. Overall, a great choice when you're trying to support your team as a frontliner
• Healer feat. Turns you into a combat medic. Being able to heal an ally back into battle will be a valuable tool when your Paladin is occupied.
• Vengeance Paladin. This subclass has a lot of synergies with Polearm Master that allows you to move from your Attacks of Opportunity. With your additional mobility effects, you can engage hostiles that threaten your squishies without having take damage yourself.

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Actions

In combat, your primary source of value will always be your Attack action. This will almost always be true for a Fighter. Actions like Shove or Grapple can occasionally be useful, but I find that supportive, "sticky" alternatives, like Sentinel, can perform much of the same utility without hindering your damage contribution for the group.

As you level up into Battlemaster, you'll have many options for special attacks, including ways to trip or push enemies into multiple situations, but a few you should focus on are things like:

• Lunging Attack (increases your reach to a whopping 15 feet!)
• Commander's Strike (Allows your Rogue to get off an extra attack for a SECOND sneak attack in the same round!)
• Goading Strike (Taunts a target, which then punishes them for approaching you when combined with Polearm Master and straight up locks them down when you get Sentinel)
• Distracting Strike (Allows your Rogue to get advantage on a ranged attack even though you're not adjacent to the target)

A strong recommendation is to pack Javelins as a side arm, as many of the attacks on the Battlemaster list don't require a melee attack, but just a weapon attack. If an enemy is engaged with your Ranger, throw a Javelin with Goading Strike and save your friend.

Answer 3

Just asking the question indicates you are already playing your character in a supportive way. E.g. Using reach zones "so I can protect our squishies".

Healing is one form of 'support'. The best way to heal your allies is to prevent incoming damage in the first place. You are good at this, so do even more of it.

Here's some detail on how this might work for a Battle Master Fighter, per comment request:

An area-denial style polearm fighter protects allies by giving foes an unpleasant choice: EITHER stay away OR probably get whacked with a big sharp stick. This whack might come with a Trip or Menacing maneuver or, worst of all, the Sentinal Feat. Foes facing this choice rarely choose to ignore the threatening fighter to go for squishier targets behind, but it happens. Ideally you also block a chokepoint.

Basically, anything that prvents foes from going after your allies, and keeps them focused on you, is a win.

Answer 4

Consider Cavalier (from Xanathar's Guide to Everything) instead of Battlemaster.

Despite the context implied by the name, most of it's abilities work just as well off a mount as on it, and it is the support fighter.

Instead of focusing on one target, Unwavering Mark gives you good reason to spread your Extra Attacks around. It will reduce your apparent DPS and provide a tangible protective effect:

[...]When you hit a creature with a melee weapon attack, you can mark the creature until the end of your next turn. This effect ends early if you are incapacitated or you die, or if someone else marks the creature.

While it is within 5 feet of you, a creature marked by you has disadvantage on any attack roll that doesn’t target you.

Sadly, the "within 5 feet" doesn't synergise with the reach provided by a polearm. You'll definitely want Sentinel, though to prevent people from walking away from you.

The bonus action part doesn't have that restriction, though. A polearm will work with it:

In addition, if a creature marked by you deals damage to anyone other than you, you can make a special melee weapon attack against the marked creature as a bonus action on your next turn. You have advantage on the attack roll, and if it hits, the attack’s weapon deals extra damage to the target equal to half your fighter level.

At L7, Warding Maneuver gives you an even more direct way to protect your friends, increasing AC and providing resistance even if the AC isn't enough to stop the attack completely.

At L10, Hold the Line allows you to make better use of a polearm, as even movement within your reach provokes an opportunity attack. It overlaps a bit with Sentinel, because it too reduces speed to zero on a hit though it gives you choices of when to trigger that stop.

L15 doesn't give the support goal anything special, but oh my is L18 awesome. Vigilant Defender grants a special reaction, usable on every creature's turn (but your own or any creature's turn you your normal reaction) that allows you to take an opportunity attack. Combined with Polearm Master, Sentinel, and suitable terrain, an L18 Cavalier can potential stop an entire horde cold by himself.