Can a character with the Polearm Master feat make an opportunity attack against an invisible creature that enters their reach?

The second benefit of the Polearm Master feat (PHB, p. 168) says:

While you are wielding a glaive, halberd, pike, quarterstaff, or spear, other creatures provoke an opportunity attack from you when they enter your reach.

The regular rules on opportunity attacks state:

You can make an opportunity attack when a hostile creature that you can see moves out of your reach. To make the opportunity attack, you use your reaction to make one melee attack against the provoking creature. The attack occurs right before the creature leaves your reach.

Obviously, Polearm Master lets you use your reaction to make an opportunity attack when a creature enters your reach, in addition to the opportunity attack any character can make when a creature leaves their reach. However, does the opportunity attack from Polearm Master follow the same restriction on needing to see the creature, or can this attack be made even without seeing the creature that enters its reach?

If an invisible creature enters the reach of a character with the Polearm Master feat, can the character make an opportunity attack against that creature?

Does Polearm Mastery have a disadvantage on adjacent targets?

Does a character that has taken the Polearm Mastery feat have any trouble with targets closer than 10 feet? i.e. standing immediately in front of them (5ft).

The feat wiki tells me this:

Polearm Master: You can keep your enemies at bay with reach weapons. You gain the following benefits:

When you take the Attack action and attack with only a glaive, halberd, or quarterstaff, you can use a bonus action to make a melee attack with the opposite end of the weapon. The weapon’s damage die for this attack is a d4, and the attack deals bludgeoning damage.

While you are wielding a glaive, halberd, pike, or quarterstaff, other creatures provoke an opportunity attack from you when they enter your reach.

It says that it keeps them at bay, does this mean no creature can get closer to attack it?

I’m thinking about something along the lines of Ranged Weapons, where when a target is adjacent (5 ft.) you have disadvantage when trying to hit them.

Aiming a ranged attack is more difficult when a foe is next to you. When you make a ranged attack with a weapon, a spell, or some other means, you have disadvantage on the attack roll if you are within 5 feet of a hostile creature who can see you and who isn’t incapacitated. (BD&D p73)

Does this make sense? I want my players to have fun using their feats but I was curious if the rules say something about this specifically.

Can you combine Polearm Master with War Caster to cast Booming Blade as enemies approach?

The Polearm Master feat (PHB, p. 168) says:

While you are wielding a glaive, halberd, pike, or quarterstaff, other creatures provoke an opportunity attack from you when they enter your reach.

The War Caster feat (PHB, p. 170) says:

When a hostile creature’s movement provokes an opportunity attack from you, you can use your reaction to cast a spell at the creature, rather than making an opportunity attack. The spell must have a casting time of 1 action and must target only that creature.

On this very topic, Mearls has said it requires an attack with the same weapon that’s granting you the trigger:

Q: Do Polearm Master and War Caster combine to allow a magic user to make a spell opportunity attack when they enter reach?
A: No – polearm master applies only if you use the weapons it lists to make the attack

Another question on this very topic: Which is likely to provide more chances to opportunity attack, Polearm Master or Sentinel (with War Caster)?

But since then, we now have spells like booming blade (SCAG, p. 142):

As part of the action used to cast this spell, you must make a melee attack with a weapon against one creature within the spell’s range, otherwise the spell fails. On a hit, the target suffers the attack’s normal effects, and it becomes sheathed in booming energy until the start of your next turn. If the target willingly moves before then, it immediately takes 1d8 thunder damage, and the spell ends.

So, with the addition of booming blade, if I have a quarterstaff + War Caster + Polearm Master, could I use my reaction to cast booming blade if someone steps into my reach?

What are the practical Opportunity Attack values for a bugbear, holding a reach weapon, with the Polearm Master feat?

I have crafted a Barbarian bugbear that uses a halberd weapon, and will take Polearm Master as a feat.

Bugbears have the Long-Limbed trait:

When you make a melee attack on your turn, your reach for it is 5 feet greater than normal.

The description of the Reach weapon property says:

This weapon adds 5 feet to your reach when you attack with it, as well as when determining your reach for opportunity attacks with it.

I am trying to determine the cut-off ranges for various situations. Making a standard melee attack is pretty straight-forward. He can attack anyone in 15′ (5′ for normal, plus 5′ for bugbear, then add 5′ for reach).

But how do I calculate opportunity attacks?

You can make an opportunity attack when a hostile creature that you can see moves out of your reach.

So my reach is generally 15′. But per the bugbear description, that extra 5′ is only when I make an attack on your turn. So his effective reach is only 10′.

So an opponent can be next to the character and safely back away 5′ because they have not left the 10’/15′ reach. But what happens at 10′ and 15′?

At 10′, they are still within my normal reach, but only on my turn. At 15′ they are leaving my reach, but I only get that extra 5′ on my turn so it would not be available as a reaction.

P.S. There is a sister question about Polearm Mastery and entering my threat range.

At what distance can a bugbear, holding a reach weapon, with Polearm Mastery, get their Opportunity Attack?

I have crafted a Barbarian bugbear that uses a halberd weapon, and will take Polearm Mastery as a feat.

As a bugbear:

Long-Limbed. When you make a melee attack on your turn, your reach for it is 5 feet greater than normal.”

Using a reach weapon:

Reach. This weapon adds 5 feet to your reach when you attack with it. This property also determines your reach for opportunity attacks with a reach weapon.”

And Polearm Mastery:

“While you are wielding a glaive, halberd, pike, quarterstaff, or spear, other creatures provoke an opportunity attack from you when they enter your reach.

Making a standard melee attack is pretty straight-forward. He can attack anyone in 15′ (5′ for normal, plus 5′ for bugbear, then add 5′ for reach).

At what distance can he attack someone coming towards him?

So my reach is generally 15′. But per the bugbear description, that extra 5′ is only when I make an attack on your turn. So his effective reach is only 10′.

Per Polearm Mastery, I can take an Opportunity Attack when they enter my reach; which is normally 15′. But I only get that extra 5′ on my turn, and since this is another creature using it’s movement, it’s not the character’s turn.

So can he attack when someone is 15′ feet away, or does he have to wait until they are within 10′?

P.S. There is a sister question about Polearm Mastery and leaving my threat range.

Does the bonus attack from Polearm mastery feats receive ability modifier for damage?

PHB page 168 says:

Polearm Mastery: You can keep your enemies at bay with reach weapons. You gain the following benefits:

When you take the Attack action and attack with only a glaive, halberd, or quarterstaff, you can use a bonus action to make a melee attack with the opposite end of the weapon. This attack uses the same ability modifier as the primary attack. The weapon’s damage die for this attack is a d4, and it deals bludgeoning damage.

While you are wielding a glaive, halberd, pike, or quarterstaff, other creatures provoke an opportunity attack from you when they enter your reach.

Does this bonus attack benefit from ability modifiers for damage?

Using shillelagh with polearm master [duplicate]

This question already has an answer here:

  • Shillelagh and Polearm Master Interaction 1 answer

If a character with the shillelagh spell and polearm master feat can they use a d8 for their second attack with a quarterstaff?

Shillelagh

For the duration thereafter, you can use your spellcasting ability modifier instead of Strength for the weapon, and its damage die becomes a d8.

Polearm Master

When you take the Attack action and attack with only a glaive, halberd, quarterstaff or spear, […] the weapon’s damage die for this attack is a d4, and the attack deals bludgeoning damage.

One could argue that the feat makes it clear that your extra attack with Polearm master says that it deals a d4, period. But one could also say that the d4 is one of the quarterstaff’s damage dice, and therefore becomes a d8 because you are making a second attack with the weapon.

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

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.

Can I attach a dagger to the end of a polearm for use with the Polearm Master feat?

In Dungeons and Dragons 5e my character uses a glaive with the polearm master feat that allows for a bonus action strike with the blunt end. Recently I acquired a dagger of venom and have a forge cleric in my party. Would I be able to attach the dagger to the end of my glaive for use with the PAM bonus action strike, or is there a rule which prohibits this?

Can I use a Spell as a reaction when a creature enter my quarterstaff reach if I have Polearm Master and Warcaster feats?

Assume that I’m a wizard, with both

Polearm Master feat:

While you are wielding a glaive, halberd, pike, quarterstaff or spear, other creatures provoke an opportunity attack from you when they enter the reach you have with that weapon.

and War Caster feat:

When a hostile creature’s movement provokes an opportunity attack from you, you can use your reaction to cast a spell at the creature, rather than making an opportunity attack. The spell must have a casting time of 1 action and must target only that creature.

and I’m holding a staff of power (It’s basically a quarterstaff).

Can I use a 1 action spell, as a reaction when a creature enters my quarterstaff reach, that targets only that creature?