Either Green needs to be able to give something besides Wolver's Dens, or Wolver's Dens need to have more variety.
We have that new Gate that started today, and while it doesn't even reach Tier 2, I thought I'd give it a try for fun. It can give Areans, but I happened to hit none of them. I hit every single Wolver's Den in the gate. There's two, maybe three variations on this map, and even those are pretty damn similar. After 5 minutes I wanted to shoot myself. Wolver's Dens are horrible. They are exactly the same map design every single time, and never spawn any different enemy...I mean I know it's a Wolver's Den, but still...give us something different once in a while, the entire map doesn't need to be Wolvers.
I mean, I know not a lot of areas have a lot of variation yet, however for some reason Wolver's Dens stick out the most. Wolvers aren't even a very entertaining monster, and unlike other monster types, they don't have any variation really either. Each Tier has the same type of mini-boss Wolver and regular monster Wolver, and it doesn't change in that Tier, so in a Gate like the new one, it's exactly the same thing over and over and over until you go insane.
I'd say you should be happy it doesn't go all the way to the Core. Wolver's Dens with those stone wolvers are even more annoying. Wolvers teleporting around every second, there's just no fun in having to kill those over and over again.. They're a challenging enemy, yes, but they don't make for a fun enemy if you throw so many at us.
I have the same problem with Ironwoods and its family members. They're easy to kill, just take ages to die. No challenge in there, similar to wolvers. It's a pure grind to kill those in my opinion. However, I think most of this comes from the lack of monster types. I've faced them way too much already without healthy change, and that's due to this little set of monsters we only have at the moment. I would love to see a lot more types of monsters and level types added. And I do mean a lot.