Works for all Survival waves and Campaign. 7-8 min average combat time for 32-35 with 3x target farm. For Nightmare, you can/should use LTs instead because of the lower mob hp/higher speed, which Warden does not excel at. Blank's build works great for that https://dundefplanner.com/map.php?load=3751
Hint 1 is on the floor at the top of the stairs, reflect at the bottom.
- Typical survival setup char-wise. (TB, 1-2 guardian chars) Upgrade everything first, then swap to whatever. 
- I do builder Warden + TB for 23-24 and 28-29. For 32-35, 2x Hunt guards on Hint 2. For the former 2, you can get away with a solo Warden if you keep Wrath up. 
- TB stands on 2, shooting at North or South crystal.
- "Required" stats are just my stats for comparison. It feels pretty safe so you might be able to get away with lower. 
- If your Apprentice/Adept builder has better armor, swapping it to Warden for this build is a good idea.
Note: If you do the secret (not gonna spoil how ;3), you get 14 extra DU. Use this as you will. 1 Wisp on each stack is a good way to use it. This might end up making some faster builds. :)