Brute taunt and -Range
It is an AoE.

Your character does not have capped defense. Depending on your AT the cap is between 175% - 225%. Your defense is not teal in the combat window, it can go higher. STOP SAYING IT IS CAPPED! The correct term is Soft Cap.
I enjoy playing in Mids. I specialize in Melee Characters, other AT's usually bore me.
Okay, but are you speaking of the taunt effect alone, or the taunt effect and the -range debuff?
Here's what MechaCrash argues (paraphrasing):
Taunt is a power available to brutes. When brutes use Taunt, a taunt effect is placed on the targeted enemy and up to 4 more* within the power's radius. In addition, a -range debuff is placed upon the targeted enemy only. The -range debuff is single target, the taunt effect is AoE.
*I think Taunt has a cap of 5, but not sure and I can't check it right now.
Here's what MechaCrash argues (paraphrasing):
Taunt is a power available to brutes. When brutes use Taunt, a taunt effect is placed on the targeted enemy and up to 4 more* within the power's radius. In addition, a -range debuff is placed upon the targeted enemy only. The -range debuff is single target, the taunt effect is AoE.
*I think Taunt has a cap of 5, but not sure and I can't check it right now.
The power is an AoE, thus the effects are an AoE as well.

Your character does not have capped defense. Depending on your AT the cap is between 175% - 225%. Your defense is not teal in the combat window, it can go higher. STOP SAYING IT IS CAPPED! The correct term is Soft Cap.
I enjoy playing in Mids. I specialize in Melee Characters, other AT's usually bore me.
Maybe I'm missing something here, but this is not obvious to me. When we look at Tanker attacks, for example, even single target attacks have an AoE taunt component. That's an example of both a single target effect and an AoE effect in a single power.
Next, we have MechaCrash claiming that the taunt portion of Brute Taunt is AoE, but that the -range rebuff is single target. (see my first post to see that quote) There might be game mechanic reasons why that can't happen, but it does seem that the reverse is possible.
Next, we have MechaCrash claiming that the taunt portion of Brute Taunt is AoE, but that the -range rebuff is single target. (see my first post to see that quote) There might be game mechanic reasons why that can't happen, but it does seem that the reverse is possible.
can always like test this on RWZ dummies with a power analyzer lol, it should show a -75% range on the combat attributes window

Anecdotal from earlier today I found when I lobbed taunt at a pack of longbow the one I targeted with taunt would rush forward to launch the sonic grenades and the others in the pack would not. I have no hard data to back that up, but it certainly seemed to happen every single x6 pack (I lead with taunt to draw out the sonic grenades before diving into the group with most of my brutes).
I'll keep an eye on it next time I use a brute with taunt.
Weight training: Because you'll never hear someone lament "If only I were weaker, I could have saved them."
I tested today using the Power Analyzer. The -range debuff of Brute Taunt only affects the single enemy targeted by the power. Surrounding enemies may be affected by the taunt, but will not be affected by the -range debuff.
Not necessarily.
Brute taunts have a 15' radius, but the radius on the -range effect is set to 0, effectively making it single target (unless two enemies somehow occupy the exact same space).
Interestingly, I noticed several oddities about it.
First is that the -range effect is not limited to PvE only. That means that the range debuff is autohit in PvP, even if the taunt effect itself misses. This appears to be intentional.
Second, there's a combat log message for PvP: "PLAYER partially hits you with their Taunt! Your range is reduced but the Taunt is not successful!" However, there's a small bug: It doesn't have the radius limited, so it will show up for everyone who was caught in the Taunt AoE but missed their to-hit check, regardless of if their range was debuffed by the single target effect or not. It also shows up if the streakbreaker forced a hit of the primary effect, when it shouldn't.
Finally, Street Justice, Claws, Broad Sword, Katana, and Kinetic Melee are missing the extra "partially hit" message for PvP.
Brute taunts have a 15' radius, but the radius on the -range effect is set to 0, effectively making it single target (unless two enemies somehow occupy the exact same space).
Interestingly, I noticed several oddities about it.
First is that the -range effect is not limited to PvE only. That means that the range debuff is autohit in PvP, even if the taunt effect itself misses. This appears to be intentional.
Second, there's a combat log message for PvP: "PLAYER partially hits you with their Taunt! Your range is reduced but the Taunt is not successful!" However, there's a small bug: It doesn't have the radius limited, so it will show up for everyone who was caught in the Taunt AoE but missed their to-hit check, regardless of if their range was debuffed by the single target effect or not. It also shows up if the streakbreaker forced a hit of the primary effect, when it shouldn't.
Finally, Street Justice, Claws, Broad Sword, Katana, and Kinetic Melee are missing the extra "partially hit" message for PvP.
This was what more anecdotal testing indicated when I ran a taunting brute against longbow again at the same settings. Nullifier I hit will run in a bit. Nullifiers in the radius lob from where they are.
Weight training: Because you'll never hear someone lament "If only I were weaker, I could have saved them."
On another thread about Provoke, MechaCrash indicated that the -range aspect of Brutes' Taunt powers is only single target, even though the taunt aspect of those powers is an AoE.
I asked for confirmation of this, but didn't receive any. I'd check city of data, but it's down at present. So I've come to the source, the Brute forums, to find out if this is true.
Is the -range debuff in Brutes' Taunt single target?