This guide will easily get you to wave 50+ on passages.
(Use the screenshots to better understand this setup)


Note: Use the minimap in the screenshots to better understand my characters location.

The basic idea here is to block off both sets of stairs (and under the third set) so that all the enemies will be forced to walk all the way to the back of the map and walk all the way down that super long hallway. That hallway, when lined with Grinders and Pounders will take care of virtually everything. All small things will die and the larger things (that happen to make it past that) will get teleported back to the gate and will go through the long hallway all over again.

Note: Use the Lightning Ring's secondary for larger enemies. If you get in trouble, use the Mana Rage Trinket's Secondary and lay down 3-4 lightning storms.

Note: Fill the hallway first, after that expand your traps the the main floor and such, you'll figure it out.

Note: Gnoll Hunters/Yeti can be a major problem at these higher levels. How did I deal with them? I used the Blunderbuss to knock them over then ran like a b*tch. These units never try to go in to the portal, they will just follow you. Eventually they all died from traps while chasing me all over the map.

Step 1: Block off the gap under the main staircase.
Step 2: Block off both sets of stairs (on the sides) with barricades.
Step 3: Setup 3-4 Grinders in front (direction enemy comes from) of those barricades to stop sappers.
Step 4: Setup all hell in the long hallway.
Step 5: Setup Teleporters at the end of the hallway (closest to portal)

See the Weapons/Traps section to get the correct equipment.

These weapons and upgrades should be selected:
(Order them to your liking of course)
1. Ring of Lightning

• Max Base Level (3 of 3)
  
• Unique #2

2. Blunderbuss

• Max Base Level (3 of 3)
  
• Unique #2

3. Pounder

• Max Base Level (3 of 3)
  
• Unique #1

4. Tar Trap

• Max Base Level (3 of 3)
  
• Unique #1

5. Arrow Wall

• Max Base Level (3 of 3)
  
• Unique #1
  
• Special #1 (Optional)

6. Barricade

• Max Base Level (3 of 3)
  
• Unique #2

7. Floor Portal

• Max Base Level (3 of 3)
  
• Unique #2

8. Grinder

• Max Base Level (3 of 3)
  
• Unique #1

9. Trap Reset Trinket

• Special #1
  
• Special #2

10. Mana Rage Trinket

• Special #1
  
• Special #2