What is reach worth?

[BarneyBent]

So I’m playing a Shillelagh-wielding Arcana Cleric with Booming Blade and a ring that doubles the range of my spells (including Booming Blade). I started a thread earlier about the best way to utilise the increased range on cantrips, and after chatting with the DM she said we could maybe work something out with a quarterstaff with reach.

So my question is, what is reach (on a Shillelagh-compatible weapon) worth?

If you compare a dagger to a whip, it’s worth the difference between a simple weapon and a martial weapon. But that’s not a perfect comparison since in all but a few cases, proficiency in a single martial weapon necessitates proficiency in ALL martial weapons. So there’s an assumption of versatility that extends beyond a simple weapon to weapon comparison.

Another comparison would be a Halberd against a Greataxe. In that case, the difference is an average of 1 damage. That seems much, much less than the difference between a simple weapon and a martial weapon (IMO). That said, the difference between a shortsword and a longsword is also about 1 damage so maybe it’s about right.

So my question is, what would you consider the value of a magic quarterstaff whose only magic property was reach? Common item? Uncommon? Rare? Equivalent of a +1 weapon? Worse? Better? How would it compare against an elemental weapon with an extra d6? Would that equate to a d4 plus reach?

[SpiderWaffle]

The Quarterstaff with reach is very similar to the spear functionally which is a really easy to get weapon. However, I think the quarterstaff was intended to be worse for pure combat stats in a vacuum and better suited for mages with spells like Shillelagh and from a flavor standpoint with arcane focus. I think uncommon would be pretty reasonable.

[MrStabby]

How much is it worth?

It depends on the game. Are feats allowed? If so pole arm mastery makes pole arms better. Pole arm mastery and sentinel combo now becomes accessible to quarterstaff users. Big increase.

Is booming blade in the game or is it PHB only or AL where players have chosen a different book. If moving 5 ft to get closer to you is gonna hurt then it is better.

What spells might the PC have? On a paladin with wrathful smite this becomes really good.

Add to that the flexibility of saving 5 ft of movement. Ability to engage and withdraw with no reaction attacks (potentially really important if allies are throwing round Ale attacks).

So probably equivelant to a rare item, but might be towards the lower end. As I said it is not a guess for all tables/characters, just from what I gleaned about yours.

[Kadesh]

In comparison to a Greatsword or Greataxe, around 1 average damage dice less, if you assume they are all built from the same theory.

[Willie the Duck]

So I’m playing a Shillelagh-wielding Arcana Cleric with Booming Blade
...So my question is, what is reach (on a Shillelagh-compatible weapon) worth?

My answer is that, for the exact reasons mentioned here, something like reach can't be quantified as simply as 'about a point of damage' or 'about the simple-martial weapon divide. It's worth is that it makes reach-BB shenanigans possible for this build. That is its value. Normally, for reach-BB to work, you need:
1) a reach weapon (whip, pike, glaive, halberd)
2) stats to support said weapon (Dex for whip; Str for pike, glaive, or halberd; Cha for any of them, but for level 1/3+ hexbladelock, depending)
3) Some way to have BB (Arcana Cleric, Sor/Wiz/War, Magic Secret, Magic Initiate)

So a War/Tempest Cleric ponies up a feat for Magic Initiate (and has a decent Str, MAD being the burden of the class), an Arcana Cleric gets martial weaponry (and now Str or Dex burden). Eldritch Knight or Hexblade or level 10+ Valor Bard can do this without feat support (hexblade with SAD). I'm not saying that this is the biggest thing ever, but part of shillelagh only effecting a weapon without otherwise great special abilities is part of the point of the spell, that limitation being baked into the power curve of the cantrip, and circumventing it being something I as a DM would only do so after much consideration. I'd say a magic item that did so would be of a relatively precious rarity level (exactly what that would be will be dependent upon your campaign).

[Mitsu]

Reach is great but only in particular cases:

1. PAM + GWM. We have to use reach weapon here as we need 2-handed polearm to apply GWM. PAM adds extra attack for 1k4 + stat + 10 which is great.

2. PAM + Sentinel. A classic. Opportunity attack -> enemy reduced to 0 speed.

3. Backline character. If you are backline character and you mostly hide behind your tanks- having a 10ft reach weapon is great so you can attack enemies from behind your front line on your turn, without having to move around too much.

4. Conquest Paladin level 7 Aura + Fear spell. You lock in place all frightened enemies around you (reducing them to 0 speed). You can then use 10ft reach weapon to attack them till they are dead.

5. Mounted Combat. having 10ft reach from back of your mount means you can get in, hit most enemies and go back without needing to use Disengage action.

Generally: reach is very good but not always.

In your case if you have ring that doubles spell range - reach polearm is great as you can git enemies with BB 10 ft from you. I would strongly consider investing in PAM so you can OA-BB them when they enter your reach so they need to either waste turn or move 5ft to you and take extra BB damage.

[Willie the Duck]

In your case if you have ring that doubles spell range - reach polearm is great as you can git enemies with BB 10 ft from you. I would strongly consider investing in PAM so you can OA-BB them when they enter your reach so they need to either waste turn or move 5ft to you and take extra BB damage.

I'm pretty sure they understand that part, and in fact, that's why they want this item. They have simply been using Shillelagh (and thus, I will assume have sub-optimal-for-combat-stat Str and Dex), and want to continue to do so.

[Man_Over_Game]

Consider the fact that it's a Battlemaster Maneuver to grant Reach. Compare it to some of the other Maneuvers to get an idea of its power level. Considering something like a conditional extra melee attack is available as a Maneuver, I'd say that Reach is roughly the equivalent of a Bonus Action attack.

[Floogal]

One disadvantage to reach: your opponents have a larger space to freely move about once they're inside your threatened area.

With a typical weapon, an engaged opponent must stay within 5 feet of you to avoid an Attack of Opportunity. With a reach weapon, the opponent can move anywhere within 10 feet of you freely, meaning you must be further from your allies to try to shield them.

Even with the Sentinel feat, anyone who happens to start their turn ten feet away from you can freely circle around you, maintaining their ten-foot distance.

[Kadesh]

One disadvantage to reach: your opponents have a larger space to freely move about once they're inside your threatened area.

With a typical weapon, an engaged opponent must stay within 5 feet of you to avoid an Attack of Opportunity. With a reach weapon, the opponent can move anywhere within 10 feet of you freely, meaning you must be further from your allies to try to shield them.

Even with the Sentinel feat, anyone who happens to start their turn ten feet away from you can freely circle around you, maintaining their ten-foot distance.

Curious, just researched this.

"You can make an opportunity Attack when a hostile creature that you can see moves out of your reach." You have a 5ft Reach with your Unarmed Strike/Improved Weapon (such as a Shield). "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."

You can still make opportunity attacks with the Reach weapon, regardless of what caused it. It's just a matter of whether you want to use your reaction at 5ft (and thus provoke when you leave 5ft) or wait until 10ft.

[Willie the Duck]

You can still make opportunity attacks with the Reach weapon, regardless of what caused it. It's just a matter of whether you want to use your reaction at 5ft (and thus provoke when you leave 5ft) or wait until 10ft.

Are you suggesting that a creature moving from 5' away from you to 10' away from you (when you have a 10' reach) would provoke an OA, given that you still have a 5' reach as well as a 10' reach?

[Kadesh]

You can make an opportunity attack when a hostile creature that you can see moves out of your reach. You have a 5ft reach due to your improvised weapon/unarmed strike, ergo, you can make an unarmed attack. However,as it's an attack, you can choose whether to attack with the unarmed strike, or the 2H reach weapon.

I can see the validity in an argument that it only out of your maximum reach, just that the rules do not make a differentiation between your different reaches.

[Willie the Duck]

Oh, I see, adds 5' to your reach "for Opportunity Attacks with it" Yeah, I don't know. Seems like quite a stretch.

:smallbiggrin:

[stoutstien]

As far a weapon balance is concerned I think reach is worth -.5 weapon damage die size

Standard 1d8 =0 (mace)
Finesse subtract one die
Heavy add one die
Thrown subtract one die
Light subtract one die
Martial add one die
Two handed add one die
Verisatile- add half die rounded up
Reach add half die rounded up.

The max die is d12 and minimum is a d4.
Example great axe 1d8 + 2 steps for martial and two handed and minus .5 for heavy so ~1d12.

a versatile staff weapon to sneak attack that had reach. It would be 1d8+1 for martial and then - 2 for finesse, reach and versatile so 1d6/1d4 twohand/one hand.
Not perfect but it's a rough guide.

[Man_Over_Game]

As far a weapon balance is concerned I think reach is worth -.5 weapon damage die size

Standard 1d8 =0 (mace)
Finesse subtract one die
Heavy add one die
Thrown subtract one die
Light subtract one die
Martial add one die
Two handed add one die
Verisatile- add half die rounded up
Reach add half die rounded up.

The max die is d12 and minimum is a d4.
Example great axe 1d8 + 2 steps for martial and heavy so 1d12.

a versatile staff weapon to sneak attack that had reach. It would be 1d8+1 for martial and then - 2 for finesse, reach and versatile so 1d6/1d4 twohand/one hand.
Not perfect but it's a rough guide.


You forgot the Two Handed option for the Great Axe. I'd probably estimate that Heavy grants 1/2 of a die and that Reach subtracts a die. This would put the Great Axe at a 1d12.5, the Halberd at 1d10.5.

If in the case of a .5 die, cut it in half and use two dice (so a 1d8.5 is actually a 2d4). If it can't be cut in half (because there's no such thing as a 1d5), then just round down (meaning a 1d10.5 would just be 1d10).

[Cynthaer]

You can make an opportunity attack when a hostile creature that you can see moves out of your reach. You have a 5ft reach due to your improvised weapon/unarmed strike, ergo, you can make an unarmed attack. However,as it's an attack, you can choose whether to attack with the unarmed strike, or the 2H reach weapon.

I can see the validity in an argument that it only out of your maximum reach, just that the rules do not make a differentiation between your different reaches.

Hold up, let's look at the actual rules again:


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.


Reach. 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 would agree that someone leaving your unarmed strike range is vulnerable to an OA with an unarmed strike even if you're wielding a reach weapon. The entry on reach weapons goes out of its way to ensure the longer reach only applies to attacks with that weapon, so as long as you're not actually attacking with your halberd, your reach is still 5 ft. No problem there.

But I think you're making two errors here when saying you could then attack with the halberd at 5 ft. First, you're inferring that there are "multiple reaches", and second, you're using a general rule to override a specific one, instead of the other way around.

I don't really object to the first one as a mental shorthand, because the distinction between "you have a 5 ft reach, and this halberd extends it to 10 ft when you're actively using it" vs "you have a 5 ft unarmed strike reach and a 10 ft halberd reach" doesn't really matter. I only mention it here because the reason "the rules do not make a differentiation between your different reaches" is that the rules don't consider you to have multiple reaches.

The second is more important. You've taken the reach rule that says it "determines your reach for opportunity attacks with it", then looked at the general OA rule and said, "Aha! The OA rule just says 'reach' and 'make a melee attack'—it doesn't put any limits on what I attack with!"

But it doesn't have to. The limit is right there in the reach weapon rule: When you're determining your reach for opportunity attacks with the weapon, you add 5 ft. The trigger and the action aren't separable here*, so you don't get to calculate reach one way for the trigger and the other way for the attack. You're either trying to make an unarmed OA or a halberd OA, and you calculate your reach accordingly for the whole thing.

* I'm only talking about how OAs work here, and it really doesn't matter whether there are other things in 5e where the trigger and the action are cleanly separated. I'm not trying to open up a general debate about spellcasting or shield bashing or whatever else.

[stoutstien]

You forgot the Two Handed option for the Great Axe. I'd probably estimate that Heavy grants 1/2 of a die and that Reach subtracts a die. This would put the Great Axe at a 1d12.5, the Halberd at 1d10.5.

If in the case of a .5 die, cut it in half and use two dice (so a 1d8.5 is actually a 2d4). If it can't be cut in half (because there's no such thing as a 1d5), then just round down (meaning a 1d10.5 would just be 1d10). yep i did. i will fix that. like i said its not perfect but its a good way to quickly gauge a weapon. special tags add a bloop in the math also

[Mordaedil]

Wait, so if you play a bugbear, are you actually hampering yourself because all of your weapons now have reach and reach seems to just be a detriment in 5e?

One of my friends just pointed out to me that the raw text for bugbears doesn't say that their reach is 5 feet extra, but that on their turn when they attack, they can increase the reach by 5 feet. This basically means you can still lock down people as your reaction is only 5 feet long, but your reach when attacking is 10 feet.

[MrStabby]

Hold up, let's look at the actual rules again:





I would agree that someone leaving your unarmed strike range is vulnerable to an OA with an unarmed strike even if you're wielding a reach weapon. The entry on reach weapons goes out of its way to ensure the longer reach only applies to attacks with that weapon, so as long as you're not actually attacking with your halberd, your reach is still 5 ft. No problem there.

But I think you're making two errors here when saying you could then attack with the halberd at 5 ft. First, you're inferring that there are "multiple reaches", and second, you're using a general rule to override a specific one, instead of the other way around.

I don't really object to the first one as a mental shorthand, because the distinction between "you have a 5 ft reach, and this halberd extends it to 10 ft when you're actively using it" vs "you have a 5 ft unarmed strike reach and a 10 ft halberd reach" doesn't really matter. I only mention it here because the reason "the rules do not make a differentiation between your different reaches" is that the rules don't consider you to have multiple reaches.

The second is more important. You've taken the reach rule that says it "determines your reach for opportunity attacks with it", then looked at the general OA rule and said, "Aha! The OA rule just says 'reach' and 'make a melee attack'—it doesn't put any limits on what I attack with!"

But it doesn't have to. The limit is right there in the reach weapon rule: When you're determining your reach for opportunity attacks with the weapon, you add 5 ft. The trigger and the action aren't separable here*, so you don't get to calculate reach one way for the trigger and the other way for the attack. You're either trying to make an unarmed OA or a halberd OA, and you calculate your reach accordingly for the whole thing.

* I'm only talking about how OAs work here, and it really doesn't matter whether there are other things in 5e where the trigger and the action are cleanly separated. I'm not trying to open up a general debate about spellcasting or shield bashing or whatever else.

I think there is also a question around "when you attack with it". When an enemy moves, you are not attacking with it - it has to trigger first. Now I am pretty sure it isnt what is intended, but I think it could be argued that your reach for opportunity attacks is 5 ft.

[Cynthaer]

I think there is also a question around "when you attack with it". When an enemy moves, you are not attacking with it - it has to trigger first. Now I am pretty sure it isnt what is intended, but I think it could be argued that your reach for opportunity attacks is 5 ft.

But that's the point of the second clause.


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.

It doesn't really get much more explicit than that. OAs trigger when a creature leaves your reach. When you're determining your reach for opportunity attacks with a halberd, the halberd adds 5 feet to your reach. Ergo, your reach is 10 ft, so you can't OA with a halberd just because someone moves from 5 ft away to 10 ft away.

The only way to get around this is to claim that "determining your reach for opportunity attacks" was not intended to apply to the OA trigger of "leaves your reach", but instead for determining where you can actually attack once the trigger happens. But this reading is absurd, because (A) it means the second clause is useless and completely redundant with the first clause, and (B) it means that you can't get an OA when the creature leaves your 10 ft radius, because that's enabled by the second clause — without it, your reach is literally only 10 ft when you're attacking, not when enemies are moving around on their turn.

At the end of the day, the correct reading is the most intuitive one and the one that has the least absurd outcomes: If you're talking about normal attacks or OAs with a reach weapon, your reach is 10 ft for all purposes. If you're talking about normal attacks or OAs with an unarmed strike, your reach is 5 ft for all purposes.

[BarneyBent]

But that's the point of the second clause.



It doesn't really get much more explicit than that. OAs trigger when a creature leaves your reach. When you're determining your reach for opportunity attacks with a halberd, the halberd adds 5 feet to your reach. Ergo, your reach is 10 ft, so you can't OA with a halberd just because someone moves from 5 ft away to 10 ft away.

The only way to get around this is to claim that "determining your reach for opportunity attacks" was not intended to apply to the OA trigger of "leaves your reach", but instead for determining where you can actually attack once the trigger happens. But this reading is absurd, because (A) it means the second clause is useless and completely redundant with the first clause, and (B) it means that you can't get an OA when the creature leaves your 10 ft radius, because that's enabled by the second clause — without it, your reach is literally only 10 ft when you're attacking, not when enemies are moving around on their turn.

At the end of the day, the correct reading is the most intuitive one and the one that has the least absurd outcomes: If you're talking about normal attacks or OAs with a reach weapon, your reach is 10 ft for all purposes. If you're talking about normal attacks or OAs with an unarmed strike, your reach is 5 ft for all purposes.

Would you still allow AoOs at 5ft with unarmed strikes? Remember, reach only applies the extra 5 ft to AoOs with that weapon - it doesn’t apply to unarmed strikes.

And if so, would you allow a player with Warcaster to cast a spell instead of make an unarmed attack?

And if so, would you allow that same player to cast Booming Blade using their Polearm instead of making an unarmed attack?

I believe your interpretation of RAW is correct, but it is also RAW that with Warcaster you can cast Booming Blade whenever an AoO is triggered. An AoO could trigger at 5ft (unarmed strike) or 10ft (reach weapon). As part of that Booming Blade you can still use your Polearm, regardless of the AoO trigger.

Obviously it doesn’t apply to Polearm users without Booming Blade and Warcaster, but they will almost always have one or both of PAM and Sentinel which more than makes up for it.

[Kadesh]

But that's the point of the second clause.



It doesn't really get much more explicit than that. OAs trigger when a creature leaves your reach. When you're determining your reach for opportunity attacks with a halberd, the halberd adds 5 feet to your reach. Ergo, your reach is 10 ft, so you can't OA with a halberd just because someone moves from 5 ft away to 10 ft away.

The only way to get around this is to claim that "determining your reach for opportunity attacks" was not intended to apply to the OA trigger of "leaves your reach", but instead for determining where you can actually attack once the trigger happens. But this reading is absurd, because (A) it means the second clause is useless and completely redundant with the first clause, and (B) it means that you can't get an OA when the creature leaves your 10 ft radius, because that's enabled by the second clause — without it, your reach is literally only 10 ft when you're attacking, not when enemies are moving around on their turn.

At the end of the day, the correct reading is the most intuitive one and the one that has the least absurd outcomes: If you're talking about normal attacks or OAs with a reach weapon, your reach is 10 ft for all purposes. If you're talking about normal attacks or OAs with an unarmed strike, your reach is 5 ft for all purposes.

The correct reading is the one the rules put down in writing. Failure to do so is not playing by the rules of the game.

And that is okay, too. Please do not derail the thread because you wish to try and debunk what is poorly written because you don't like the fact it is poorly written. Find better things to do with your life and time.

[SpiderWaffle]

There was a Crawford tweet about reach weapons AoO being after leaving 10', not 5' to 10'. You're holding it with two hands also, so your not currently in a state to even strike unarmed.
All the reach weapons are 1d10, heavy and two handed sans the "special" horse mounted lance with 1d12. I think if the reach quarterstaff had those same properties it would be uncommon or rare, pretty reasonable.

[AttilatheYeon]

Wait, so if you play a bugbear, are you actually hampering yourself because all of your weapons now have reach and reach seems to just be a detriment in 5e?

One of my friends just pointed out to me that the raw text for bugbears doesn't say that their reach is 5 feet extra, but that on their turn when they attack, they can increase the reach by 5 feet. This basically means you can still lock down people as your reaction is only 5 feet long, but your reach when attacking is 10 feet.

No bugbears are kinda weird. They only have extra reach on there turn. So most OAs will still be at there base weapon range. Course this also means you have to move forward to get an OA.

Like i said they are weird.

[Mordaedil]

No bugbears are kinda weird. They only have extra reach on there turn. So most OAs will still be at there base weapon range. Course this also means you have to move forward to get an OA.

Like i said they are weird.

It ends up being kinda helpful, as otherwise my bugbear totem warrior barbarian would be incredibly inconvenienced by the sub-class abilities that state "5 ft. of you" when it should say "in your range".

[AttilatheYeon]

It ends up being kinda helpful, as otherwise my bugbear totem warrior barbarian would be incredibly inconvenienced by the sub-class abilities that state "5 ft. of you" when it should say "in your range".

Yup, but the mechanic is weird.

[BarneyBent]

There was a Crawford tweet about reach weapons AoO being after leaving 10', not 5' to 10'. You're holding it with two hands also, so your not currently in a state to even strike unarmed.
All the reach weapons are 1d10, heavy and two handed sans the "special" horse mounted lance with 1d12. I think if the reach quarterstaff had those same properties it would be uncommon or rare, pretty reasonable.

Is there any rule that states you must have a free hand to unarmed strike? Kicks, headbutts, etc all count as unarmed strikes. I see no reason to disallow those while wielding a two handed weapon.

[Man_Over_Game]

Is there any rule that states you must have a free hand to unarmed strike? Kicks, headbutts, etc all count as unarmed strikes. I see no reason to disallow those while wielding a two handed weapon.

On the contrary, a weapon is only wielded with two hands when you're attacking with it (so you can still do somatic components for spells with a two handed weapon). In other words, there are rulings supporting your claim.

[Mordaedil]

Yup, but the mechanic is weird.

Agreed. It should have been exteded reach, but most 5ft abilities should really be "reach" extensive, but then we go back to 3.5 in terms of difficult combat...

[SpiderWaffle]

Is there any rule that states you must have a free hand to unarmed strike? Kicks, headbutts, etc all count as unarmed strikes. I see no reason to disallow those while wielding a two handed weapon.

Yes for attacks and actions made on your turn that totally makes sense, you could choose to hold your weapon with only one hand and have a free hand to strike, just like with somatic components. You have 6s after all. A reaction would seem a bit different to me though, you can't during other creatures' turns decide to be holding a weapon with only one hand or with two hands whenever you want as a sort of free bonus reaction not counting towards your reaction.
It's certainly is ambiguous and Crawford, like usual, does a horrible job of clarifying or making a good rule system. Quotes from Crawford:

""Your reach" means whatever reach of yours is relevant at the moment."
https://twitter.com/JeremyECrawford/status/782999583869718528

"If you have more than one reach, a foe provokes an opportunity attack when it leaves any of them."
https://twitter.com/JeremyECrawford/status/725193622581293056

"The reach property applies only when you attack with a weapon. Any use beyond that is up to the DM."
https://twitter.com/JeremyECrawford/status/502520711395557376

"How does a reach weapon work with opportunity attacks? An opportunity attack is normally triggered when a creature you can see moves beyond your reach (PH, 195). If you want to make an opportunity attack with a reach weapon, such as a glaive or a halberd, you can do so when a creature leaves the reach you have with that weapon. For example, if you’re wielding a halberd, a creature that is right next to you could move 5 feet away without triggering an opportunity attack. If that creature tries to move an additional 5 feet—beyond your 10-foot reach—the creature then triggers an opportunity attack."
http://dnd.wizards.com/articles/features/sageadvice_july2015

I'd be inclined to think you'd need to hold a one-handed reach weapon like a whip and then either have a free hand or a non-reach weapon in the other hand.

There's a also large debate over similar poor clarity of these rules by vetted rpg stack members, with no clear consensus reached:
https://rpg.stackexchange.com/questions/46352/does-a-reach-weapon-allow-you-to-threaten-squares-10-feet-away-or-not

At least one thing is clear with 5e though, it will vary drastically from DM to DM and never be clear.

[ZorroGames]

Snip

At least one thing is clear with 5e though, it will vary drastically from DM to DM and never be clear.

That has been true since the early 1970s with OD&D.

[BarneyBent]

Yes for attacks and actions made on your turn that totally makes sense, you could choose to hold your weapon with only one hand and have a free hand to strike, just like with somatic components. You have 6s after all. A reaction would seem a bit different to me though, you can't during other creatures' turns decide to be holding a weapon with only one hand or with two hands whenever you want as a sort of free bonus reaction not counting towards your reaction.
It's certainly is ambiguous and Crawford, like usual, does a horrible job of clarifying or making a good rule system. Quotes from Crawford:

""Your reach" means whatever reach of yours is relevant at the moment."
https://twitter.com/JeremyECrawford/status/782999583869718528

"If you have more than one reach, a foe provokes an opportunity attack when it leaves any of them."
https://twitter.com/JeremyECrawford/status/725193622581293056

"The reach property applies only when you attack with a weapon. Any use beyond that is up to the DM."
https://twitter.com/JeremyECrawford/status/502520711395557376

"How does a reach weapon work with opportunity attacks? An opportunity attack is normally triggered when a creature you can see moves beyond your reach (PH, 195). If you want to make an opportunity attack with a reach weapon, such as a glaive or a halberd, you can do so when a creature leaves the reach you have with that weapon. For example, if you’re wielding a halberd, a creature that is right next to you could move 5 feet away without triggering an opportunity attack. If that creature tries to move an additional 5 feet—beyond your 10-foot reach—the creature then triggers an opportunity attack."
http://dnd.wizards.com/articles/features/sageadvice_july2015

I'd be inclined to think you'd need to hold a one-handed reach weapon like a whip and then either have a free hand or a non-reach weapon in the other hand.

There's a also large debate over similar poor clarity of these rules by vetted rpg stack members, with no clear consensus reached:
https://rpg.stackexchange.com/questions/46352/does-a-reach-weapon-allow-you-to-threaten-squares-10-feet-away-or-not

At least one thing is clear with 5e though, it will vary drastically from DM to DM and never be clear.

I think that’s pretty clear. If you have multiple reaches, you get an opportunity attack if a creature leaves any of them. But you can only use the weapon associated with that reach.

Note that for the purposes of reactions, you are considered to have a free hand while holding a 2 handed weapon if not attacking with it, hence the ability of an Eldritch Knight to cast Shield while wielding a 2 handed weapon.

So based on that, you can make an unarmed strike as an AoO against an opponent leaving a 5 ft radius while wielding a weapon with reach. You cannot, however, make an attack with your reach weapon.

Warcaster and Booming Blade overrides that, by RAW, allowing you to cast a spell, and Booming Blade requiring you to make a weapon attack, but one might houserule that a) you can cast Booming Blade with an unarmed strike (technically disallowed by RAW unless you have natural weapons), and b) you can only use that unarmed strike BB when using a 5ft AoO. Which is probably what I’d do.

[Isaire]

I'm not sure what you guys conceptualise an attack of opportunity as, but I'm not going to ask my dm to be able to headbutt a monster fleeing from me as that is absolutely absurd. Punch? Sure. But you need a free hand for that, and you can't both have a few hand for punching and be wielding a halbard at the same time.
Any other rule strikes me as a little crazy to be honest..

[BarneyBent]

I'm not sure what you guys conceptualise an attack of opportunity as, but I'm not going to ask my dm to be able to headbutt a monster fleeing from me as that is absolutely absurd. Punch? Sure. But you need a free hand for that, and you can't both have a few hand for punching and be wielding a halbard at the same time.
Any other rule strikes me as a little crazy to be honest..

It’s been made clear that you have a free hand when holding a two handed weapon for the purposes of casting spells as a reaction (e.g. Shield). Why would the same logic not apply to unarmed strikes?

[Kadesh]

I'm not sure what you guys conceptualise an attack of opportunity as, but I'm not going to ask my dm to be able to headbutt a monster fleeing from me as that is absolutely absurd. Punch? Sure. But you need a free hand for that, and you can't both have a few hand for punching and be wielding a halbard at the same time.
Any other rule strikes me as a little crazy to be honest..

I think not reading the rules is a little bit crazy, but if you're houseruling, that's okay, because it's your game. Might be worth advising people of your change to the core game rules, though.

[SpiderWaffle]

It’s been made clear that you have a free hand when holding a two handed weapon for the purposes of casting spells as a reaction (e.g. Shield). Why would the same logic not apply to unarmed strikes?

If that's true then it would seem to follow, yes. Was this tweeted?
Rules still don't make it explicit for one to definitely know on their own sadly, need lots of tweets to patch the rule frame work up.

[BarneyBent]

If that's true then it would seem to follow, yes. Was this tweeted?
Rules still don't make it explicit for one to definitely know on their own sadly, need lots of tweets to patch the rule frame work up.


The PHB errata says the two-handed property only applies when attacking with the weapon, not when simply holding it.

https://media.wizards.com/2015/downloads/dnd/Errata_PH.pdf