Wizardlands are dimensions added by Conquest Of The Wizardlands. Personal pocket dimensions owned by wizards, Wizardlands can only be accessed by entering a valid Arcane Address into the Pocket Dimension's portal generator. Be warned that entering an invalid address, or anything else, will instead send the player to Diggle Hell.
Wizardlands are randomized, like the dungeon, and feature monsters, chests, and other loot; however, unlike Strange Dimensions and Diggle Hell, the monsters featured will be scaled to the level of the dungeon the address was found on, making them much safer. Caution should be taken at earlier levels, as a certain lever trap may spawn two extremely dangerous clones who are indeed like five levels higher than you are.
Once you have entered a Wizardland the only way to return to the dungeon is to beat it by locating the exit portal. The exit portal is often, but not always, guarded by a special monster, and always has an artifact resting near it as a reward for clearing the whole level.