Hunted Demons Forge

The quickest and easiest way I have found to do this find a crucible map that gives you a lot of gold very quickly.

The map I have been using is by GHOSTDOG 360 and is called 30,000 golden. To find this map go to browse maps > All creators > GHOSTDOG 360 > 30,000 golden.
(GHOSTDOG 360 should be on the first page of results)

There is a total of just over 30,000 gold to be had on this map. The amount you get is related to the amount of kills you get. The more kills the more gold.

Its not the easiest map to do but it is easy enough and gives a good reward. I was averaging 20,000 per go and it takes less 10 minutes to do. If you struggle with this map GHOSTDOG 360 also has made a map called 10,000 golden which is easier but obviously will take a bit longer to get the amount of gold you need.

Credit goes to GHOSTDOG 360 for making a great map and Angrymagnox for finding the map

The solution by DROPKICK HOPE86 is spot on. I just wanted to add a little tweak to it that makes it truely easy for everyone and kinda cheap at the same time lol.

When you start the GHOSTDOG 360 level rather it be the 10,000 or 30,000 play as caddoc and stand just at the start of the stairs so elara stands behind you the entire time. Once the enemies start spawning just spam and hold down the right bumper to continue casting caddoc's levitate spell so that they becom easy pickings for elara. Inbetween waves collect your mana vials then rinse and repeat. all the gold elara makes from kills goes towards your total ammount so you will have no problem getting your achievement.

Props to Dropkick Hope86 for being the first to note the ideal map for this solution.

However, this solution will also discuss a strategy to actually survive the listed room.

First and foremost, what you need to do is go into Crucible, then "Browse maps". Using the D-Pad, press Right a couple of times until the category shows "All Creators". Scroll down until you see GHOSTDOG360, and select that one. Then, you'll see his maps:

30000 Golden
10000 Golden
99999 Golden

Select 30000 Golden.

Within this map, you will have maxed abilities and some good equipment to survive. You'll be on a limited time, facing against Skag (infected) wargar, the dual-wielding kind, and they know how to destroy you pretty well. I highly recommend using E'lara so that Caddoc can keep the enemies busy. I suggest you stick with the Fast bow (as E'lara) and spam Pyre Blast (the explosive arrows) most of the time. One shot will not kill enemies, unless Caddoc has them levitating, so if he's blocking mostly, shoot them a few times before using Pyre Blast. It may still take more than one Pyre Blast, so be prepared for that. Once you play a couple of times you'll see what I mean and understand how many shots it takes and at how much health you should start spamming it. Mana is abundant, so don't be worried. Stay close to Caddoc so that he can tank the enemies (draw their attention and absorb their attacks) and after he swings a couple of times, hit them with a Pyre Blast. It should be enough to kill them, and you'll notice that for every kill, you get gold out of it. Once in a while Caddoc will also lift them in the air with his magic, and this is a perfect time to stay within the wind radius (so any enemies pursuing you get caught in it) and use Pyre Blast on them. If he happens to Battle Charge you, feel free to use that if you don't want to spam Pyre Blast, but the enemies usually drop mana bottles over health bottles, so you shouldn't have problems spamming your Pyre Blast as long as you don't miss too often.

On the top left is your gold count and the top right is Caddoc's. The objective is to survive the time limit and the enemies, while accumulating as many kills as possible. When you're done, the door to the next room opens, which happens to be another Obelisk/White Portal room (which you can just sprint through) and then there's the exit.

If you're on point, you can nail about 30,000 gold each time you play. For this achievement you have to get to Crucible Tier 27 which is 100k gold.

This strategy also works for

Also, if you have a good Caddoc strategy, feel free to comment on this solution and post your strategy, and I'll add it to the solution and give you credit for it. I seem to suck with Caddoc on this map, and so I couldn't come up with a good solution for him.