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As stated here, you can use cantrips like booming blade and green-flame blade to trigger Sneak Attack under given conditions, naming one is you got advantage on your attack.

Now, one of the factors that can give advantage is hiding - being unseen and unheard - and then attacking.

Can I use those cantrips while hiding for sneak attacks, given that they have verbal components?

I would argue yes, because the attack is part of the spell and is performed sort of simultaneously with the verbal components, so it doesn't break the hiding advantage.

I'm not asking, if I can hide in combat to the get sneak attack, just if I can hide and use cantrips to trigger it without losing advantage from being hidden.

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    Sneak attack from hiding probably doesn't work in melee - https://rpg.stackexchange.com/a/91373/27377 – enkryptor Aug 10 '17 at 10:42
  • @enkryptor There are problems with the answers on that question - primarily the fact that they fail to take lighting into account. – T.J.L. Aug 10 '17 at 13:34
  • How exactly do you hide? – enkryptor Aug 10 '17 at 13:50
  • @enkryptor by taking the hide-action and succeed in a stealth check. Or what do you mean? – PSquall Aug 11 '17 at 10:53
  • @PSquall I mean in-game. What your character was attempting to do, so the GM asks you "make a Stealth check"? Or did you announce "I make a hide action" explicitly? (that would be weird, since there are many places where you can not hide, regardless of the check) – enkryptor Aug 11 '17 at 12:49
  • You can't just use hide unless you have some ability that allows you to hide while being observed or has gained sufficient cover from the target. – Mindwin Remember Monica Aug 12 '17 at 01:48
  • @enkryptor Of course you need somewhere to hide to use this action. A Lightfoot halfling can hide behind a bigger ally, others may hide in a haystack. The enemy might know you are in there, but still can't see you. And yes, it depends on the GM if you have a place to hide. "can I hide in the bush next to the soldier?" - "yes you can with disadvantage, cause he saw you going into it." - "Ok, I try to hide there". – PSquall Aug 12 '17 at 21:56
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    But when you attack, you go out from behind the ally, and become visible again. – enkryptor Aug 12 '17 at 22:40
  • @enkryptor But if you can reach the enemy from behind your cover, then you don't need to move out if your cover, you just attack. The enemy might know you are there, but doesn't see you attack coming. After that, you are obviously visible. – PSquall Aug 12 '17 at 23:20
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    @PSquall that's why I ask you, how exactly did you hide. – enkryptor Aug 13 '17 at 12:50
  • Related question. – AntiDrondert Aug 24 '18 at 08:37

5 Answers5

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If you are hidden from the target at the time of casting then you get advantage:

Unseen Attackers and Targets (PHB p.194)

When a creature can’t see you, you have advantage on attack rolls against it.

The green flame blade spell, as an example, has this in the description:

Green-Flame Blade (Sword Coast Adventurer's Guide p.143)

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.

The action taken to cast the spell is also the action that "contains" the attack. If the target is unaware of the caster at the time of casting they are equally unaware of the caster at the time the attack is made.

Therefore the attacker has advantage on the attack roll and may use sneak attack.

Protonflux
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    In 5e D&D, an "action" isn't something that happens at one time. You spend your action on the attack action, and that lets you attack a certain number of times over your turn. These attacks don't all happen at the same time, and being hidden for part of your action does not guarantee you are hidden for your entire action. Do you have rules text that distinguishes the "multiple attacks part of action", where you can be hidden for one but not another, and the above "part of action"? – Yakk Aug 10 '17 at 14:18
  • When you attack a creature in melee, it definitely can see you, can't it. – enkryptor Aug 10 '17 at 14:27
  • @Yakk the action is "cast a spell" (PHB p.192). You can cast a spell from a hidden position. After your "cast a spell" action, which cannot normally be broken up in the same way extra attack can, you have given yourself away and unless you are invisible then the best you have is some kind of cover. This specific spell has the melee attack as part of the "cast a spell" action. You cannot cast the spell, move, take a bonus action or whatever and then do the attack. So your comment does not apply to this case, it is a thing that happens at one time. – Protonflux Aug 10 '17 at 15:30
  • @Protonflux I understand that is your understanding; I'm asking for a rules citation backing that understanding. – Yakk Aug 10 '17 at 15:33
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    @enkryptor definitely? No. "In combat, most creatures stay alert for signs of danger all around, so if you come out of hiding and approach a creature, it usually sees you." (PHB, p. 177) Usually is definitely NOT definitely. – Luke Aug 11 '17 at 02:56
  • @Luke I guess PHB says "usually" because not all creatures can see at all, a creature can be blinded, etc. Anyways, my comment was based on this answer https://rpg.stackexchange.com/a/91373/27377 – enkryptor Aug 11 '17 at 10:26
  • @yakk the citation is the "cast a spell" action. Nowhere does it say that this can be split up in any way, so it can't be. It is a singular action (lower case a). Further a spell can be cast from a hidden position, all already established. What more do you need? – Protonflux Aug 11 '17 at 15:36
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    @enkryptor The question explicitly states that he's not asking about hiding in combat. He has asked to assume that he otherwise meets the criteria for a sneak attack. The way I read it, it boils down to 'If I can sneak attack by hitting a creature from hiding, can I also sneak attack by saying "hiya!" while hitting a creature from hiding?' – Luke Aug 13 '17 at 23:53
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Yes, you can attack while hidden with a cantrip

Your specific request is of attacking while successfully Hidden by using GFB or BB cantrips.

The use of the cantrip (or of an attack) is not the trigger for losing your hidden status. The hidden status is removed when your attack hits or misses.

Jeremy Crawford via Sage Advice confirms this:

If you attack while hidden, you have advantage on the roll, and you reveal your position on the hit/miss (see PH, 194–5).

Just like you can make an attack while hidden to get advantage, you can cast the spell while hidden to get advantage. It is the after effects of those actions that result in the loss of your Hidden status.

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NotArch
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  • It was about range attacks, wasn't it? – enkryptor Aug 10 '17 at 15:34
  • @enkryptor Yes, although ranged vs melee really doesn't make a difference. The mechanic is when the hidden status is lost. – NotArch Aug 10 '17 at 15:41
  • It makes a difference - when you attack someone in melee, you need to get close to them first. You lose the hidden status earlier in this case. – enkryptor Aug 10 '17 at 16:43
  • PHB says "you reveal your position on the hit/miss" but that doesn't mean you can not reveal your position by any other means. – enkryptor Aug 10 '17 at 16:43
  • @enkryptor Possibly - depends on the environment. There are always mitigating circumstances that the DM can rule for, but the general rule is on the hit/miss. Saying a verbal component breaks hidden when attacking with a weapon (either ranged or melee) doesn't seems unfair. Especially considering the rules are Invisibility and what breaks it. – NotArch Aug 10 '17 at 16:48
  • "Hidden" isn't a condition, so it can't be "lost". You have to actually be detected. It's not clear to me that having a location revealed means you are seen. – user-781943 Nov 12 '20 at 09:01
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I'd say when you cast a spell when hiding you still surprise them. When using the spell(green flame blade) you make an attack. So yeah, why wouldn't it?

Green flame blade:

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

Unseen attackers:

"Unseen Attackers and Targets", PHB p.194

Combatants often try to escape their foes’ notice by hiding, casting the invisibility spell, or lurking in darkness.

When you attack a target that you can’t see, you have disadvantage on the attack roll. This is true whether you’re guessing the target’s location or you’re targeting a creature you can hear but not see. If the target isn’t in the location you targeted, you automatically miss, but the DM typically just says that the attack missed, not whether you guessed the target’s location correctly. When a creature can’t see you, you have advantage on attack rolls against it.

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  • @T.J.L. It would be nice if people would elaborate why they don't agree. Am I not reading the rules correctly? I'm kinda left in the dark here. – Toofle Aug 10 '17 at 12:28
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    @Toofle The upvotes on comments are often indicative - it's likely the objection is your assertion that advantage applies to both attacks, as the querent pointed out in his comment. That said, it would be nice if people left detailed comments, but they are not required nor expected to. – T.J.L. Aug 10 '17 at 12:30
  • "Surprised" condition isn't relevant. A creature can see you and still be Surprised. If you attack a creature in melee, it probably see you, unless you are invisible or attack in the complete darkness. – enkryptor Aug 10 '17 at 13:53
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Yes, you can use cantrips with verbal components to sneak attack, or else the Magical Ambush feature gained at 9th level from the arcane trickster class wouldn't make sense. PHB page 98 says:

Starting at 9th level, if you are hidden from a creature when you cast a spell on it, the creature has disadvantage on any saving throw it makes against the spell on this turn

If casting a spell with verbal components from hiding would make the caster lose the benefit before the spell takes effect, then this feature wouldn't be that useful, as there are few spells without verbal components.

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-2

Booming Blade and Green Flame Blade cantrips require the caster to make an attack, but they don't affect the attack's conditions. If you have (dis)advantage on the attack roll, you still have it.

If you are invisible, you get sneak attack

If you are under the Invisibility spell effect, or fighting in darkness, the enemy cannot see you, so you get the advantage:

When a creature can’t see you, you have advantage on attack rolls against it.

You have advantage, so you can apply the sneak attack damage as well.

If you just attack from hiding, you don't get sneak attack

As being discussed in this answer, to get the advantage, you have to be unseen when you attack. If you attack in melee, the enemy can see you:

In combat, most creatures stay alert for signs of danger all around, so if you come out of hiding and approach a creature, it usually sees you.

(PHB, p. 177)

The enemy can be Surprised though, so you still get benefit from the ambush, but you cannot apply the sneak attack damage.

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  • In combat, so it may not apply to the initiating round. Also, think of backstabbing, you could easily approach someone without notice. – lynxlynxlynx Aug 10 '17 at 19:21
  • What's wrong with the initiating round? There is no surprise round in 5e. – enkryptor Aug 10 '17 at 20:13
  • @enlkryptor it usually sees you, as you quoted, so there are circumstances where the sneak attack can be applied. Your statement is too strict. – Mudo Aug 11 '17 at 02:04
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    @Mudo It wasn't my statement, it is the approved answer https://rpg.stackexchange.com/a/91373/27377 – enkryptor Aug 11 '17 at 10:25