Does this spell affect creatures above the caster?

Ah, Spirit Guardians. The cleric's version of a breath attack.

In the PHB, this spell requires concentration. It doesn't state it here. I have to keep arguing with players and bring out the PHB over and over to show them. The spell is too strong for it not being a concentration.

Quote from Raul_5 >>

In the PHB, this spell requires concentration. It doesn't state it here. I have to keep arguing with players and bring out the PHB over and over to show them. The spell is too strong for it not being a concentration.

I was wondering bout 'concentration' too.  Is that maybe what the "C" in the black diamond beside the duration represents?  There is no legend ...

Quote from VancouverDave >>

Quote from Raul_5 >>

In the PHB, this spell requires concentration. It doesn't state it here. I have to keep arguing with players and bring out the PHB over and over to show them. The spell is too strong for it not being a concentration.

 

I was wondering bout 'concentration' too.  Is that maybe what the "C" in the black diamond beside the duration represents?  There is no legend ...

 Yes, that's exactly what the "C" means.

That can't be what the C in the black diamond means. I get that C on several of my Paladin spells that are instantaneous. Bless, Divine Favor, Protection from Good & Evil, Thunderous Smite, Shield of Faith...not one says anything about having to concentrate. They are either immediate or 10 min durations. So the C MUST mean something else. 

Although I assumed it meant Concentration and then noticed Concentration was not mentioned in the spell description, I assumed it was meant to mean something else. I thought, after my post, I should have done my due diligence before posting anything on a forum, so I pulled out the PH. It does, in fact, say Concentration on all those spells I listed above. However, since the spell write up in the D&D Beyond DOES NOT say concentration, is it possible, through some errata I am not familiar with, it's changed to simply a duration spell? And they just forgot to remove the C, I've noticed other mistakes on D&D beyond, so forgetting to remove the C from spells that are no longer concentration based, I could understand. 

Anyways, I just wanted to say that after posting that, I did refer to the PH and realized I was mistaken. But maybe not. 

The "C" in the black triangle means that it is indeed a concentration spell.

Just wanted to make that 100% clear if anybody was still confused.

As far as concentration goes...

Normal activity, such as moving and attacking, doesn't interfere with concentration. The following factors can break concentration:

• Casting another spell that requires concentration. You lose concentration on a spell if you cast another spell that requires concentration. You can't concentrate on two spells at once.
• Taking damage. Whenever you take damage while you are concentrating on a spell, you must make a Constitution saving throw to maintain your concentration. The DC equals 10 or half the damage you take, whichever number is higher. If you take damage from multiple sources, such as an arrow and a dragon's breath, you make a separate saving throw for each source of damage.
• Being incapacitated or killed. You lose concentration on a spell if you are incapacitated or if you die.

It does, that's the little C icon before the duration  

Using the Spirit Guardians throw walls?

AoE spells need Los to effect targets,  but  this is conjuration spell , “you call forth spirits” and the damage done to the enemy  is from them.  With Conjuration spells your characters do not do damage, the Items or creatures you summon do the damage for you. And since you summon extra planer “ If you are good or neutral, their spectral form appears angelic or fey (your choice). If you are evil, they appear fiendish.” And most spectral forms move freely throw walls.

This makes the spell one of the most OP of the game.