What's so good about the "blade" cantrips?

[Gavin O.]

According to a lot of guides, the "blade" cantrips, Booming Blade and Green-flame Blade, are highly desirable, but I cannot understand why. Yes they scale where a character's melee attacks don't, but so does every other damaging cantrip and those don't require you to also have competent weapon attacks. I can see why you might want them if you have quicken spell or War magic or some other way to abuse them, but not otherwise.

Am I missing something?

 

[Blue]

According to a lot of guides, the "blade" cantrips, Booming Blade and Green-flame Blade, are highly desirable, but I cannot understand why. Yes they scale where a character's melee attacks don't, but so does every other damaging cantrip and those don't require you to also have competent weapon attacks. I can see why you might want them if you have quicken spell or War magic or some other way to abuse them, but not otherwise.

Am I missing something?

They are desirable in a specific case - you are playing a melee-based character without access to Extra Attack.

They use your melee attack ability (usually STR or DEX) to apply, so you don't need to have a high spellcasting ability score. This is a big difference from all the other damaging cantrips, and it's generally a big shift. For those that want it, it's a big positive shift, for those who don't it's a big negative shift.

The damage is also quite nice, especially when you factor in that as a melee-based character there will be other damage increases (magic weapons, fighting styles, hex - whatever the build & party do).

EDIT: They sometimes beat out Extra Attack even if you have access to it. Also, it's available before Extra Attack so even a character that will eventually get it may want the cantrips early on.

 

[Herosmith14]

And at least in theory, I find Booming Blade a bit more useful than Green Flame Blade(both are still really good). Pick up war caster, OA BB, and the thunder damage goes through immefietely cause they're already moving of their own free will.

 

[Grue AC]

And thanks to Hexblade CHA casters can melee without being MAD.

 

[Ganders]

They break one of the core rules of the game: the separation between melee attacks and spells. That's useful in various clever exploits.

Melee attacks scale in frequency (extra attack, bonus action attacks, AOO, Haste, etc) while spells scale in damage directly (cantrips by level, upcasting, etc). To make up the difference, melee also get bonuses such as backstab, orcish fury, and strength bonuses much more often than spells get int bonuses. For melee classes, getting a bit of cantrip-scaling damage added to their attacks is attractive.

Also, most class abilities are triggered by 'when you attack' or 'when you hit with a weapon attack' so they won't work with spells. For caster multiclasses, getting access to some of those with a cantrip is a good enough reason, even more so if they have a way to still use their casting stat for the attack.

 

[Blue]

Also, most class abilities are triggered by 'when you attack' or 'when you hit with a weapon attack' so they won't work with spells. For caster multiclasses, getting access to some of those with a cantrip is a good enough reason, even more so if they have a way to still use their casting stat for the attack.

Actually, those trigger just fine with these spells. IIRC Sage Advice had a good breakdown. What doesn't trigger is "When you use the Attack Action", which is different from an attack. You are using the "Cast a Spell" Action, it just happens to include an attack. So anything that triggers of an attack, a hit, a melee-weapon attack, and the like will still trigger, but anything that wants the Attack action (like two weapon fighting) will not. (PHB 192)

 

[FrogReaver]

According to a lot of guides, the "blade" cantrips, Booming Blade and Green-flame Blade, are highly desirable, but I cannot understand why. Yes they scale where a character's melee attacks don't, but so does every other damaging cantrip and those don't require you to also have competent weapon attacks. I can see why you might want them if you have quicken spell or War magic or some other way to abuse them, but not otherwise.

Am I missing something?

They can give a big damage boost to rogues and clerics. I don't think I've found a good use for them outside those 2 classes.

 

[Volund]

BB is pretty good for an EK with War Magic from level 7-10. After the second Extra Attack at 11 it's not as good. After that I still might use GFB if there is another monster within 5' to tag with fire damage.

Falling into the OP's category of "or some other way to abuse them", my tempest cleric 16 can do spectacular crit damage with BB, Divine Strike, Destructive Wrath, and his Staff of Thunder and Lightning to throw in some extra max lightning damage. He's best friends with Battle Masters and Shield Masters and anyone else who can give him advantage on melee attacks.

 

[smbakeresq]

I use them with certain cleric and bard builds to fill a character idea. For example right now I am playing a Dragonborn Bard in a Greyhawk Campaign with 1 level of life cleric and then lore bard rest of way. The idea is she was pushed into the clergy on Dragons Island in but then realized the way to spread the word about her people was to wander the lands and collect and retell the stories of others. Of course being a dragonborn and worshipping dragons means you are built for combat, so a skald seems like the best idea. Dragonborn are majestic of course of course so Bard makes sense also.

So I took BB as a spell secret to keep going with that theme and the energy theme of dragons and dragonborn. Its thematic also to smack someone with an attack that also blasts them with energy and is flashy. It also works with Warcaster feat and then Dissonant Whispers (you can use BB for the OPP ATT and get the damage bonus right away as you scream foul oaths at them) and also use it for the OPP ATT generated by Command (flee.)

The other blade spells are ok but they put this PC (and others that get into melee but really are not built for it) into range of more than one enemy which is bad for you. Lightning Lure is poor since other cantrips do more and pulling isn't that great or useable. It isn't a blade spell but in the same section so I put it here.

 

[mikal768]

They can give a big damage boost to rogues and clerics. I don't think I've found a good use for them outside those 2 classes.

They can also be useful for classes which might be able to get bonus damage based on elemental affinities. Draconic Sorcerer, Celestial Warlock, and so on.

And at least in theory, I find Booming Blade a bit more useful than Green Flame Blade(both are still really good). Pick up war caster, OA BB, and the thunder damage goes through immefietely cause they're already moving of their own free will.

Except that the enemy can choose to stop at any time, including after being hit by the OA, and thus not take the damage. This could backfire if you're a class which doesn't necessarily want the enemy to stop and do a full attack in front of you. Just something to be aware of.