World of Van Helsing: Deathtrap

This solution is split into 3 parts. Strategy and map choice, tips and choosing a scenario:

Choosing a scenario:
You access the scenario option by picking a normal story level and then you can change the level between tier, scenario and endless. (You may have to completed tier 1 to attempt these).
Once chosen, you then have the option of adding modifiers to the level, you'll want to do this until the difficulty is at least 20 but it can be more.

We did this simultaneously with the maximum difficulty scenario; however I did a few practice runs and I will say if you want to knock this one out before you're ready to do the full difficulty, I would leave out the blue stars as they definitely add a lot of challenge and repetition (the respawning enemies one in particular.)



Strategy:
Did this as 2 level 40 sorceresses. 1st level. Pick a side lane and then group together in the middle when needed. There is a good mix of enemies and resources are low so gun turrets and voltaron coils are strong starts for mechanical towers.Mystic Traps we chose Freeze or Fire. Mechanical traps we chose acid but really whatever you have maxed. Finally for mystic towers, olympus and freeze towers. A maxed freeze tower with the freeze enemy perk can buy you a lot of time.

Tips:
Two last tips and they are more general but make a big difference.
1. Standing in the way in such a way that the enemies are continuously on your floor traps makes that lane easier and faster as they continue to rake in damage.
2. Don't be afraid to use potions and tank a bit longer, potions are fairly plentiful throughout the campaign and as end of level rewards.

Good luck!

Update: If you think you're underlevelled for this I would do a number of endless attempts on the first level and you will level up very quickly, especially as a two.