How can hunger of Hadar be used effectively?

Question

How can the 3rd-level spell hunger of Hadar be used to deal damage effectively?

• Although the spell's area covers a 40-ft. diameter and creates difficult terrain, enemies can dash through it or out of it and be dealt little damage.
• The spell's blinding effect doesn't help the rest of the party much: devil's sight can't see through it—the area's just black not of darkness.

The damage just can't compare to fireball under the best of circumstances. Does the spell have some secret use or benefit that I'm missing? Why is this seemingly subpar spell a 3rd-level spell?

Answer 1

The spell is very good, in the right circumstances or against the right opponents. The use cases are:

• You're fighting an opponent with significant defences but not a lot of HP. Cold is rarely resisted by enemies (so far), and the cold effect neither allows a save nor requires an attack. That 2d6 damage can affect almost any creature with no chance of failure, at least once.
• You've cornered the enemy (or they've cornered themselves). If you can fill the enemy's region of the battlefield entirely with this spell, and your allies can block off the only way(s) out, then the enemies are probably dead, even if they were significantly above your level. They can't leave the area because your allies are in the way, and they are unlikely to hit your allies because they are blinded (no save), while your allies have neither advantage nor disadvantage to hitting them via the cancellation rules. Each turn they all take 2d6 cold damage (no save) and maybe 2d6 acid damage. The spell lasts up to a minute so that's definitely 20d6 cold damage to everything in the area, and maybe 20d6 acid damage as well, if the spell plays out its entire duration. Two full castings is enough to take out an adult red dragon, if you could somehow keep it stuck in the area. That's two castings of a third level spell possibly taking out a CR 17 creature. Now, this use case is pretty uncommon unless you set it up yourself, but you can usually set it up pretty okay for encounters that take place in small rooms, by having allies close and bar the doors immediately after your casting.
• You're fighting zombies, skeletons, or other mindless creatures that just march towards you and attack no matter what. You can set up a perimeter where they stand in the bad stuff and you don't and kill them all just as if they were cornered, except you don't have to block off the exits and in fact may want to not do so to allow more of them to pour in. Given their speeds, hps, and saving throws, skeletons won't even make it to your line half the time, and Zombies will die before getting there more often then not. Especially if you are playing certain older D&D modules, where these creatures may be encountered in groups of !50!, a single spell easily capable of slaying as many as 320 such undead with a single casting is quite formidable.
• You need to escape down a tunnel, street, or similar linear path less than 40 feet across. While most enemies are smart enough not to wander into the spell's area and stand there, you can use that to your advantage. Cast the spell behind your party while you are fleeing, and have your allies guard the edge as above for a round or two. If the enemies try to force their way through, you keep them back and kill them all. If they don't, you flee and they are delayed for several full rounds before they can follow you. Even with enemies who you can't fight at all, the total concealment and area of difficult terrain can help your party out significantly, even though it means not dashing for a round.
• Your party is fighting a single opponent in melee in the open and have it surrounded. Maybe it's the big bad, if not this is probably a waste of a third level slot. You cast the spell 43 ft or so above your opponent, blinding and damaging them but leaving your allies uninhibited. They all have advantage on attacks v.s. the enemy, who has disadvantage on attacks and takes 2d6 or 4d6 damage a round.
• Your last name is Whateley. The spell doesn't just kill and blind stuff, it opens a gateway to the dark between the stars, the realm of the Great Old Ones. If you were hoping to call forth the spawn of Yog-Sothoth, Shub-Niggurath, or similar beings, the spell would be a good place to start. Indeed, you can actually hear whispers and stuff through the Gate-- possibly they can hear you too. Certainly, if you were so inclined and properly prepared, you might eschew the typical uses of the Gate for one-way travel to said realm of Utterdarkness and Insanity. The consequences for doing so, and the likelihood one any particular entity or entities crossing through the portal while the spell is active normally, is a matter of setting.
• You wanna kill a Godling. Say you're a Warlock with the Great Old One patron, or your BBEG is a Warlock with a Great Old One patron (or just a Great Old One), and you've decided that Great Old One's gotta die. This spell lets you (depending on the Old One) pop open a portal to where it is, so you can throw stuff through without actually going there. Maybe, like, oil and a torch? How many hp does The King In Yellow have, anyways?

Answer 2

The spell has benefit related to battlefield control, as well as dealing damage.

The area of the spell is heavily obscured, so anyone within will be effectively blinded and noone will be able to see in area to target creatures. In addition to this, noone will be able to see through the area of the spell, so everything that is on the other side of the spell will not be visible. This in itself will stop many spells from finding their target.

Also, any creature that starts within the field will might be able to dash out, but if they have to move all the way through, it would take 80 feet of movement, and most creatures don't have that much, even when dashing.

Answer 3

One way I really like to use this spell is by finding a way to situate yourself directly above where you cast it (whether you can fly above it or find a way to get on top of a pillar of sorts) then you cast it right beneath you trying to get as many enemies inside it as possible. Then if you combo it with the Grasp of Hadar invocation and use Devil sight to get a negate magical darkness, you can just sit above the sphere and continually pull enemies back into it. another bonus you can get is by casting Plant Growth over the area (or getting one of your party members to if you aren't an Archfey Warlock) that way the enemy can essentially only move a maximum of fifteen feet even with the dash action. They will never escape this spell if done correctly.

Answer 4

Dash action is compromised both by the inside being difficult terrain and by blindness.

The location the caster centered the darkness matters. If I set it with 30' in front and 10' in back, an enemy that is blinded and unable to tell boundaries will face a dash of 30'+30' through difficult terrain the long way, leaving them just inside the area.

At that the repelling blast invocation combined with eldritch blast is nasty.
The eldritch blast splits into 2 beams; when it hits, each beam knocks back the target 10 feet (blast is not reduced for difficult terrain).

The target takes the initial 2d6 damage, runs to the edge and ends for another 2d6. On the next turn, they get repelling blasted back into the area of effect for another 2d10 (if both hit). On the start of their next turn take another 2d6. Still being inside the dark area, they can't see so direction matters. This sets up the chance to run 30' (out 20 and back 20 - just inside, because as they exit terrain changes to normal for movement.)

If they dash out and you blast them again, you're pushing them back 20' into the darkness dealing another 2d10, then they take 2d6 more starting the next round. If they moved normally and could now attack, as long as they are not pushed back by the front line before the warlock blasts them again, they would finally be clear.

Fighters stopping movement just at the wall exit for the warlock to blast them back is very effective.

In the above combination, it offers 2 rounds of damage, up to 4d10 + 8d6, for being inside the dark area. If they use dash there is no attack on you or your friends.

And just because you can't see and light does not travel doesn't mean a fireball or other area effect spell won't work as well. Combo hunger of Hadar to halt them, then fireball the area.