I saw an approach where cross-bow/stone-staff, wind-belt and morph-ring were the primary weapons and the traps taken were push-traps, spring-traps, haymakers(or zappers) , barricades, brimstones (for sappers and runners), coin-trincket and one extra trap/trinket(cant remember correctly).
This strategy is kinda tricky and there are huge risks involved.
The first few levels, you will see yourself windbelt-ing the orcs into the lava pit (tough to get money this way). The core essence of this strat is to have haymakers in the bridge-zone (bridge?) with some damage dealing trap (probably the one that i forgot - scorcher may be). The rest of the path till this will be laid with push-traps and spring traps facing the pit, so that the small ones fall into the pit and the bigger are taken care by the primary attack plus the haymaker+scorcher combo.
The bridge ares is the only kill box you can have with no barricades. I mentioned barricade in the list above since some of the orcs will fall in the side-walk area and then take that path to the rift. Some people prefer to block the side paths so that they walk back considerable distance and then go thro the traps again. May be, the barricade can be skipped in favour of steam-trap/ice-vent for slow (or tar in case of warmage, but then you wont get the morph-ring). Place the brimstones at the beginning of the opening and just before the rift, so that if runner/sappers come first they get burned instantly. If not, let them escape and the last brimstones will take of that.
Surviving this way will be very tough. Let me know how it goes (I failed at it :D ). If you succeed please make a video and share. Hope this helps!. Happy killing orcs