What are the rules for attacking a creature inside a Wall of Fire?

Question

If I cast wall of fire, surrounding the Ogres, in a ring shaped position, and my two fighter teammates attack them, will they succeed?

You create a wall of fire on a solid surface within range. You can make the wall up to 60 feet long, 20 feet high, and 1 foot thick, or a ringed wall up to 20 feet in diameter, 20 feet high, and 1 foot thick. The wall is opaque and lasts for the duration

...

One side of the wall, selected by you when you cast this spell, deals 5d8 fire damage to each creature that ends its turn within 10 feet of that side or inside the wall. A creature takes the same damage when it enters the wall for the first time on a turn or ends its turn there. The other side of the wall deals no damage.

Wall of fire's description clearly says the wall is opaque, which means light does not pass through, but you can always try to guess the location of the creature inside.

• But is it too hot to swing a sword through and not burn your fists?

  Using a dagger and attacking would be simply impossible not to pass a whole hand through it and to avoid 5d8 damage it deals.

• Is it harder for our ranger to shoot an arrow through since it is hard to see through?
• Will the wizard's spells pass through or does he have some kind of disadvantage?
• Will grappling work?
• Will shoving work?

I will try to explain the scenario in this poorly drawn image in Microsoft Paint:

Answer 1

The wall is opaque but doesn't otherwise stop attacks.

Since the wall of fire is opaque, creatures inside can't be seen and they can't see you. Thus:

When you attack a target that you can’t see, you have disadvantage on the attack roll. [...] When a creature can't see you, you have advantage on attack rolls against it.

(PHB, p. 194-195)

This means:

• Advantage and disadvantage cancel out for melee, ranged or spell attacks between creatures on opposite sides of the wall.

• Creatures on one side of the wall may roll a Dexterity(stealth) check to become hidden to foes on the other side of the wall, requiring attackers to guess which locations to target with their attacks.

• Nothing in the spell description specifically says that making attacks through the wall will inflict damage on the attacker.

• Nothing in the spell description specifically says that grappling or shoving are affected.

• However, the description of wall of flame does say that a creature who "enters the wall" takes damage. A DM could quite reasonably rule that grappling, shoving, and making melee attacks with some weapons (short ones) constitute "entering the wall", and impose damage in those cases.

• Any spells that target a creature or point that the caster can see cannot target inside the wall of fire.

• Spell effects extend through the wall (the description of wall of fire doesn't say that they don't), so spells that affect an area that originate from outside the wall can affect creatures inside it normally.

• Note that many spells that are attacks (for example, fire bolt), don't target a creature the caster can see, just one within range. So these spells can be used against creatures inside the wall.

Answer 2

Attacking and casting spells through the wall

Most of what you are asking can be explained by the PHB section on Unseen Attackers and Targets

When you attack a target that you can't see, you have disadvantage on the attack roll. This is true whether you're guessing the target's location or you're targeting a creature you can hear but not see. If the target isn't in the location you targeted, you automatically miss, but the DM typically just says that the attack missed, not whether you guessed the target's location correctly.

(PHB p. 194)

In this case, all of your attacks will have disadvantage and you have to guess the ogres' location. This includes your fighters' and your rangers' melee and ranged attacks.

Since you cannot see the targets, any spell that specifies that you must see the target of the spell will not work (assuming you want to target the ogres or the ogres' area inside the wall of fire).

Technically to make a melee attack through the wall with a non-reach melee weapon you must enter the wall itself, and thus you will take damage. The same will apply for Shoving and Grappling through the wall because these are simply special types of attack actions.

Answer 3

As a medium sized character using a sword, you threaten a 5' radius around you, meaning you reach into and can attack those spaces. By virtue of reaching in, you are subject to the Wall of Fire.

With that in mind, I'll just go through these point by point:

• But is it too hot to swing a sword through and not burn your fists? You will be burned if you attack with your sword as you'll need to reach into (and through) the wall of flame to attack.
• Is it harder for our ranger to shoot an arrow through since it is hard to see through? Yes, the Ranger is effectively blinded for the purposes of attacking the ogres because they are blocked by an effect that is opaque, which means the criteria for Heavily Obscured.
• Will the wizards spells pass through or does he have some kind of disadvantage? Disadvantage for spells with attack rolls (see Ranger answer), no impediment if using an AoE provided the AoE originates in a location the Wizard can see, the Ogres cannot be targeted with spells that require the caster to see the target (i.e. Hold Monster).
• Will grappling work? I can't see how you could grapple someone on the other side of a Wall of Flame without putting your arm through said wall.
• Will shoving work? Same answer as grappling.

Answer 4

You must also remember that the wall of fire is opaque on both sides, meaning that those on the inside are heavily obscured to those on the outside as well as those on the outside are heavily obscured to those on the inside. Both parties are essentially blind to each other.

So, using the example, the ranger firing an arrow at the ogre would have disadvantage because he can't see through the wall, but simultaneously, he would also get advantage because the ogre can't see it coming. The advantage and disadvantage would cancel each other out and it would be a straight roll.

Similar circumstances are seen with the Darkness or Fog Cloud spell. Unless one party somehow has the ability to see the other, they are on equal ground as far as advantage/disadvantage is concerned.