When is it better to choose Hideous Laughter over Cause Fear as a Great Old One TomeLock?

Question

I'm trying to decide between Cause Fear and Hideous Laughter for my Dwarven Great Old One TomeLock who has just reached second level. I've chosen a non-melee build for my character, (trying to avoid Eldritch Blast spam), and I've take Eldritch Mind and Mask of Many Faces as my second level invocations. I don't think they would make a difference though.

Currently the group is split in to two groups: My character, who has teamed up with the Sorcerer and the Thief; and the other group which comprises of a druid, and a fighter. The group being split up may change at some point.

I've already discussed this choice with my group, and I'm leaning one way, but I wanted to open the question up, to see if I'm missing anything.

Here are the main points of comparison between the two spells I've noticed:

Comparison point	Cause Fear	Hideous Laughter
Range	60ft	30ft
Components	Verbal	Material, Somatic, Verbal
Duration	same	same
School	Necromancy	Enchantment
Save stat	same	same
Condition imposed	Frightened	Prone, Incapacitated
Negated by	Constructs, Undead, Frightened immunity	Intelligence scores of 4 or less
Scales with level?	extra targets	no scaling

It looks like the key differences in favour of Cause Fear are Range, Components, Conditions imposed and scaling. The only thing that Hideous Laughter might have over Cause Fear is that it would effect Constructs, Undead and misc other creatures with immunity to being frightened (a summary of which can be found on Reddit). I don't know how many of those would also not be effected because they have an intelligence of 4 or lower (a table of which can also be found on Reddit)

The conditions imposed may or may not swing either way, I can't tell.

RPGBOT.Net also pegs them both at three stars on the wizards spell break down (the only full class that has access to both), but for the Great Old One gives the 1st level spells from the expanded spell list four stars. For Cause Fear, under the warlock spells break down it says:

[Unlike with Hideous Laughter] targets are able to attack (albeit with Disadvantage) and cast spells, and resistance/immunity to fear is common.

Under the review of Hideous Laughter, for wizards:

The best comparison at this level is to Cause Fear, which doesn’t hinder foes as much as Hideous Laughter, but they also don’t get another save whenever they take damage.

Without directly involving designer intent, it feels weird to have a spell on to the Great Old One's expanded spell list that would seem objectively worse (unless the conditions imposed by Hideous Laughter are that much better/more appropriate to play style) than one they get by default.

So that begs the question, in what situation is knowing the Hideous Laughter spell better (e.g. most rounds of enemies actions wasted, or similar) than Cause Fear, especially (but not solely) at lower levels? I'm looking for either play experience, or some other critical factor I'd missed about the spells.

_{n.b. I'm completely ignoring how each spell is flavoured, as I'm hoping I could either justify or reflavour either spell to fit my character's theme.}

Answer 1

Either is a good choice, their uses vary with the situation

I've used both spells. Your challenge is to try and figure out which one fits the situations that you expect to be in.

Currently the group is split in to two groups: My character, who has teamed up with the Sorcerer and the Thief; and the other group which comprises of a druid, and a fighter. The group being split up may change at some point.

Cause Fear - break up the foe's groups

Up through level four for sure (and up to level six if you want other level 3 spells as your first level 3 choices) if your general aim in support of your party is to get enemies to be frightened of you / disrupt groups, then cause fear is a good choice.
Caveat: once you get to level 5, and can get the level 3 spell fear, cause fear becomes a little less useful since fear can get a whole crowd of enemies running away from your party - cause fear is limited to making one, two or three enemies suffer the frightened condition. On the other hand, cause fear allows you to pick and choose whom to inflict the condition upon without getting your allies caught in fear's area of effect.

Tasha's Hideous Laughter - shut one enemy down.

If you don't want your target to get away, and you want them prone such that your allies get advantage on melee attacks, Tasha's is a great way to neutralize one enemy (and if it's something like an ogre, immobilizing that monster is a good tactical choice). Your thief will get advantage on attacks and trigger sneak attack. In your current situation, Tasha's fits your group well. But I'd still swap to cause fear at level 3 since both your rogue and your sorcerer ally can make ranged attacks on any frightened enemy.

Tasha's Incapacitated condition is good against spell casters

Tasha's Hideous Laughter inflicts incapacitation, which specifically breaks concentration. (Addresses in this answer and also this one).

That can be potentially quite valuable at any level if you are up against spell casters a lot.

My bard kept Tasha's Hideous Laughter until level seven or eight - it is a great use of level 1 slots in support of our melee characters. Since your PC is a warlock, with that level scaling feature for their spells, I'd let Tasha's go at level 3 and, if you don't have another choice, grab cause fear since you can have an impact on two enemies, rather than one, for the next couple of levels. Tasha's inability to be "cast at a higher level" is a shortcoming. You have a five person party; when they do get back together, breaking up enemy groups allows your party to have a substantial edge in combat for a few rounds.

Note: once I hit level 5 with my Warlock, neither spell suited my needs. I chose fear since I wanted to be able to break up groups of enemies. (At level 9 she still has it, but that DM tends to send swarms at us).

Recommendation for your Warlock in your situation

Tasha's for levels 1 and 2, since your mini-party is a bit more vulnerable (sorcerer and rogue aren't tanky at all) - locking down a foe is a big help. Switch to cause fear for levels 3 and 4 to break up groups of foes.

Replace it with a better spell at level 5 or 6 - there are so many good choices.

Answer 2

The conditions inflicted are different.

Incapacitated is straight-up action denial, and prone grants advantage. Frightened only denys actions to threats that are currently out of range (generally melee), and is otherwise just disadvantage.

At low levels there isn't any scaling, so Hideous Laughter is the more potent effect there. Because of the way that warlock spellcasting functions, it's quite plausible you'd switch out either before Cause Fear would be scaled to larger groups.

it feels weird to have a spell on to the Great Old One's expanded spell list that would seem objectively worse

Expanded spell lists are for flavour, not for potency. In theory spells of the same level should be equally powerful.