Use one or two Radioactive Blue potions in preparation.
Be sure you have at least 316,350 gold (plus travelling costs) on hand.
Go to the Catacombs. Immediately buy the Obelisk of Slumber from the trapsmith. You need this trap; no other trap can substitute. Use it with the Fan Base and Radioactive Blue cheese.
This area behaves much like the Mousoleum did before; tough mice, but great rewards. You'll see some old mice from the Mousoleum, and some new mice. They are of a new group; the "Forgotten Mice" group. This type is best caught using an "Arcane" trap, like the Obelisk of Slumber.
You have 3 goals here:
Catch a Keeper Mouse with the Keeper's Candle. This is the key to the locations, the Forbidden Grove and the Acolyte Realm. Do not go to those places yet.
Collect 632,700 gold to buy the Mysterious Blueprints from the General Store.
Note that there are also blueprints for a trap called the Obelisk of Incineration. Although it is slightly stronger than the Obelisk of Slumber, it's not worth the gold and resources you'll need to craft it. Just go straight for the Mysterious Blueprints, as it makes a much better trap.
Collect 12 pieces of Scrap Metal, dropped by the Scavenger Mice here.
The Mysterious Blueprints are used to craft your next trap. Before crafting it, make sure you have:
At least 3,393,600 points
1 Mysterious Blueprints (of course)
1 Onyx Stone
12 Scrap Metal
3 Magic Essence
Magic Essence is obtainable by smashing SUPER|Brie+. Find out how to obtain SUPER|Brie+ here.
Once you have those items (check it twice!), unequip your Obelisk of Slumber (by equipping another weapon), and smash it with your Hunter's Hammer in the crafting panel. You'll get 1 Obelisk Parts.
Craft the Obelisk Parts with the other ingredients above (except the points :p) to get your Arcane Capturing Rod Of Never Yielding Mystery (or the ACRONYM for short).
If you accidentally smashed the Obelisk of Slumber while lacking ingredients, you may reconstruct it by crafting the Obelisk Parts with the Bead of Slumber from the General Store. It'll set you back 2,000 gold, but that's better than having to buy it again.
Once you have crafted the ACRONYM, you should start raking in gold really quick. In fact, it is recommended that you stay here for a while, going back to the Laboratory for more potions if necessary, as you'll be needing lots of gold in the next areas.
When going back to the Laboratory, keep using the ACRONYM, but switch to the Dehydration Base for the increased Luck.
Try to collect about 1.8 million gold (yes, you'll need it), as much Scrap Metal as possible (at least 18), and stock up on Radioactive Sludge.