Kryta / Kessex Hills: Tower of Nightmares
Considering next content coming Tuesday, 26 November (Fractals), you might get this achievement done. That being said, maybe this short (LOL

) tips will help:
The first 2 floors are straight forward and can be soloed fairly easily with condition removal and decent heals. Don't fight anything and keep moving. If you do die it's back to the waypoint at the beginning. There are checkpoints on each floor in the tower, once you reached for the first time, you can return to them after paying to waypoint (by talking to the robot in each level) and then the additional charge per floor, 3 silver for second floor and 5 silver for the third, and even then can only be accessed after you've won through the first time.
The third floor is the biggest killer. There are a couple of nasty chokes and plenty of vets and elites running around. While there's a few "safe" areas free from contamination, mobs are constantly being pulled into them. Someone with a lot of stealth may be able to make it through solo, for all others will be a challenge. Was only able to do it once alone and then the "kill everything" portal event had just been cleared ahead of me. The roaming mobs would have overwhelmed a single player especially as agro seems to stick for quite a while. A group of five or so should be able to make it through so long as they don't leave anyone behind. Singles can pug or wait on one of the infrequent larger groups to help pull them through. On the other hand, smaller groups and solos should never stop to rezz death players unless downed (or except for an "instant up" skill). You will die too many times before learning that lesson. On the other hand, don't expect to be rezzed, unless you see on map, some commander tag with large group incoming to your spot.
On the long ramp to the final boss, there's catches in the floor taking anyone on auto run go right over the edge. Funny for everyone else as there's no checkpoint here and the 3rd floor has to be rerun, after paying the toll to get back up. The first set of diving goggles are at the corner of the top platform. Jump to the left, not right, as there's a branch right above the water and it will kill you. Either way, if you jump pay the toll and rerun the 3rd floor to get back.
Again, when you reach the very top of the tower (above level 3). You will find the Tricolor chest and the entrance to the final story instance The Nightmare Incarnate. Make sure you combine the 3 different colored keys together to form a tri-key, for you can open the tri-key chest at the top of the tower which can contain some rare stuff. From the mail, you get 1 of each (blue, pink and green keys), and, by doing multiple runs between levels and do the chambers, some more keys will be given as rewards or radom drops. However, you can also buy/trade them ONCE PER DAY (all set or the missing color) from the vendor located at Kessex Hills in the camp just west of the Tower, where once Marjory Delaqua was.
About the LAST BOSS in the tower: everyone seems to want a group for the toxic hybrid fight. Wrong. He's much/much easier as a solo, especially if you want the mini-pet krait Nimross (it lights up). The fights inside are pretty straightforward. Cannot highlight ranged attacks enough. Between toxic stalks and fighting while dodging laser circles, it really speeds things along while avoiding damage. For that matter, the hybrid is primarily a melee fighter.
Tip for the 3 portals room: destroy them and run out for here, leave quickly to access the arena where the last boss is. This is all what you need from here (destroy the portals to unlock the vines/roots for the next fight, and if you are able to RANGE the portals, you don't need to fight any foes in this room, just aim to portals 1 by 1).
For the hybrid itself, it doesn't seem to like attacking at the very edges of the room so if stalks and minions are dealt with you get some breathing room. Harder to get through the 3rd floor than to solo the dungeon.
Finally, if you are in a group and want the other jumping achievement, after beating the hybrid and selecting your reward there's a semi-transparent portal in the se part of the room. Going out leads to a branch over Kessex Hills with diving goggles. Problem is if the instance owner leaves the dungeon before you get out the portal (you get drug out as well and no portal for you). If you are successful, jump and pay the toll to get back to the third floor, you can't do both jumps on the same trip.
Good luck and fun within