...'less' obvious deadly hazards however....

What does "a direction that is horizontal to you" mean? Also, is this spell any good compared to other 4th level spells? Its one of the few bard exclusive spells, and it doesn't feel very good.

Not-vertical. Basically, “along the ground.”

Quote from 1paper1clip >>

What does "a direction that is horizontal to you" mean? Also, is this spell any good compared to other 4th level spells? Its one of the few bard exclusive spells, and it doesn't feel very good.

 I haven’t used it, but being able to control movement sounds pretty good, especially if there’s a wall or something to keep them against. Helps out a spell caster with aoe or wall spells 

If a bunch of enemy are around you. Bard casts this and the wizard casts arcane gate, plops them all out 500ft in the air.

What?

How powerful is this spell? It seems like it would pair well with with ranged attacks and mobile melee fighters, allowing you to attack without retaliation with impunity. However, against ranged opponents it seems much less useful. It would let you bring them inside the range of your melee fighters, but the range is so short that you probably can't catch any ranged opponents in it anyway.

So, compared with hypnotic pattern:
- no friendly fire
- about twice bigger area
- much shorter range
- effect doesn't end when target takes damage
- not useful against ranged opponents
- target can still attack if you are not careful
- uses 1 level higher spell slot

Compared with fear:
- no friendly fire
- about twice bigger area
- much shorter range
- no debuff to the victim
- target can still attack if you are not careful
- uses 1 level higher spell slot

It fills mostly the same role as fear and hypnotic pattern. Situation dictates which is the best:

- compulsion wins when there is a risk of friendly fire

- hypnotic pattern is the best against ranged opponents

- fear wins if you can keep the opponent from escaping.

So, it might situationally be worth the higher level spell slot. 

Hmm... What are the possible directions you can designate? Compass directions seem obvious, but can you choose

- away from you or towards you? 
- clockwise or counterclockwise around you?
- clockwise or counterclockwise around themselves, that is, spinning in place? As shown by Ottos irresistible dance, a creature can spend their movement by moving in it's own square.

All of these directions are horizontal to you. Making enemies spin does not grant attacks of opportunity, but it would make the spell much more predictable. Also, while it wouldn't move them to hazards, it would keep them in them. Combine with firewall for kebab or with spike growth for a cheese grater effect... 

The spell categorically states that you can't force them into deadly hazards like fie or pits as examples. Any area effect spell such as a wall of fire or spike growth would cause damage and they could not be compelled to cross into it, or stay in it. At best you could cause them to exit the area of effect on a particular side. However a DM might even determine that spell has no effect if the target is inside an area effect spell, as any movement would be causing them to move into/through a deadly hazard. 

This spell is great for a bard/cleric/paladin to force a melee attacker way from them and get an attack of opportunity as they exist and/or force an enemy to run through other players melee range forcing attacks of opportunity multiple times. it's also a great option to gain distance in a chase scene, or force an enemy onto a different path in a maze, or break a line of sight/distance spell requirement, such as witch bolt. Could also be a great cinematic action causing a break in morale as soldiers watch their captain flee a battle.

Not every spell is about maximizing damage.

For the longest time I thought "horizontal" meant like "left or right from your position." It just means you can't force something to burrow or fly upward, right?

(Pre-cast) Hallucinatory Terrain and turn that spike/lava/acid pit into a normal levelled plain (or something non-threatening)

Swoop on in while invisible, break invisibility by casting compulsion and march their sorry asses to the pit of doom

"Mwahahaha" - Melon Lord

So I built an order domain city watch cleric and this spell makes me feel more like an arrest based spell effectively you compell them towards the jail cell.

I know it doesn't say in the spell description, but is there a limit of "creatures you can see within range and that can hear you"? I mean, that could be a hell of a lot of creatures in the right scenario..... I know they all have to make an individual save but still, feels like a pretty meaty spell for a 4th level.

I have literally never heard of this spell before lol I've been involved with DnD for like 5 years how has this happened?!

Quote from Sniperwes20 >>

If a bunch of enemy are around you. Bard casts this and the wizard casts arcane gate, plops them all out 500ft in the air.

 ... Okay that is broken... I love it!

Quote from Najonin >>

Not-vertical. Basically, “along the ground.”

Fast friends is also something to consider for single targets 

Spike growth specifically looks like normal plants, so you could compel them into that

Quote from capnvespa >>

The spell categorically states that you can't force them into deadly hazards like fie or pits as examples. Any area effect spell such as a wall of fire or spike growth would cause damage and they could not be compelled to cross into it, or stay in it. At best you could cause them to exit the area of effect on a particular side. However a DM might even determine that spell has no effect if the target is inside an area effect spell, as any movement would be causing them to move into/through a deadly hazard. 

This spell is great for a bard/cleric/paladin to force a melee attacker way from them and get an attack of opportunity as they exist and/or force an enemy to run through other players melee range forcing attacks of opportunity multiple times. it's also a great option to gain distance in a chase scene, or force an enemy onto a different path in a maze, or break a line of sight/distance spell requirement, such as witch bolt. Could also be a great cinematic action causing a break in morale as soldiers watch their captain flee a battle.

Not every spell is about maximizing damage.

 I think you (surely) meant "not every spell *has to be* about maximizing damage." The specific wording on Spike Growth in particular makes it at least reasonably compatible with Compulsion.

Careful about imposing your view of the game onto others. They are likely playing/running it for different (and equally valid/fulfilling) reasons than you are.

Quote from Sniperwes20 >>

If a bunch of enemy are around you. Bard casts this and the wizard casts arcane gate, plops them all out 500ft in the air.

 Nope. From Arcane Gate: You create linked teleportation portals that remain open for the duration. Choose two points on the ground … The portals are two-dimensional glowing rings filled with mist, hovering inches from the ground