Some advanced info on Dundef
Armor Cap Values
Each tier of armor has a max value (cap) that it can reach with any stat.
Without set bonus:
Myth / Trans / Supreme / Ult / Ult+
360 / 420 / 500 / 600 / 700
With set bonus:
468 / 559 / 680 / 840 / 980
Coals and Cubes as Currency
As of 1/7/2014, the exchange rate is:
1 coal = between 12 to 15 Billion Mana
1 cube = 6 coals
Coals and cubes can either be farmed (click their links above), or obtained by trading with other players for mana and items.
What's the Fastest Way to Level Up?
The fastest map for gaining XP is Tavern Defense. On nightmare pure strategy (much easier than NM campaign), it gives about 2 Mil XP per wave. Running the NM HC campaign gives about 40 Mil XP.
What's the Fastest Way to Farm Good Gear?
Lab assault, when done properly, can give many rewards quickly. Average time for Insane Hardcore is 2 minutes per run. Average time for NM HC is 3-4 minutes per run.
Both InsHC and NMHC can give armor up to ultimate++. NMHC consistently gives better accessories though. Newer players can strive to beat Lab in order to farm gear for beating harder maps. A good setup for beating lab is: Jester, DPS myth or trans armor, and a BF drill.
Another option is King's Game, Nightmare Hardcore Survival Mixmode. However, it is much more difficult than Lab and requires strong builders.
How Can I Find More Advanced Info and Get Help with the Game?
There is an active chat group on Steam called the DDFreeRunsByRequest.
Many players there can answer questions and help you run maps.