An overscaled cMags / Hood may very well be the hardest node in all of PVE! The only thing that even comes close is the Ares/Bullseye/goon combo. Are there any other contenders? Yes, I know its all relative to your personal scaling. I personally have never finished the Gauntlet so I can’t really comment on the ending nodes…
The overscaled OLD cMags/Hood node 
I think the Hood with 2 muscles, and the Torch with 2 snipers are both harder, because bad tinykitty happens way faster there.
I think Thor (3*) + Grenadier X 2 in one of the Simulator was the hardest, though back then stuff only scaled to 230 and you had pre nerf Spiderman so it was doable, but it was basically you win by turn 3 or you weren’t winning at all.
I think New C.Mags/Hood is harder. Stopping 8 red and 10 blue and 15 yellow is pretty difficult against an 8000 HP Hood.
I also think Family Reunion VII is pretty difficult, if easily gimmicked, since the C.Mags change. Both the hardest PvE nodes in history are in TaT.
395 XF 395 Deadpool 395 Thor (pre nerf) was a bit difficult as well on Gauntlet.
The node with, what was it, Old Devil Dino + Spidey (so you couldn’t use him) +Old mStorm? was pretty infamous in its day
Venom/Yelena/Lieutenant team stun, heal, steal your ap
OK, That node would have been EASY if I wasn’t limited to Dock ock and Daredevil or whatever the dumb Heroic Roster was shakes fist
I don’t remember what order characters were released in and when exactly the scaling shift happened, but from my perspective dealing with a max level (whether it was 395 or the old max level) cMags blue and red on every single turn culminating in the inevitable purple, without XForce or lazyDaken or anyone as a crutch, scarred me in a way the node doesn’t today
Torch + 2 green feeder goons in Prodigal Sun is imo the hardest node in PvE.
From turn 4 on, you could be looking at 4000-5000 damage per turn.
I quite dislike the Dedpool/Hulk/Devil Dino one in the Deadpool event.
The Hood/Mags node is where I use the Mega Whale Drop 
. As soon as I start the TaT event, my first thought is “Crap, this has the Hood/Mag Business Partner node. I hate that one!” That node and others like it are why I make sure to get my DP points everyday! On my second account I already have over 400k, but that’s only for casual play. I don’t even bother with nodes like these with that roster. But my main one only has about 120k DP points left. It’s the only sure way I know that I can beat them.
I wasn’t around when the game first started. I started playing a little before the Spidey nerf. I didn’t even have him yet, so that didn’t affect me. But I recall others saying that the PvE lv cap was 250. But D3P changed it to 395 to compensate for Spidey, Rags and C Mag infinite blue and others. What I want to know is, now that they have all been “balanced”, when will it go back down?