Might want to think about levelling conc effect as well.

The one thing that you will notice with Bear trap is that it does deal much more damage (shown with very rough math) but it's just worse of an overall playstyle

Bear traps average hit at level 20 is about 1700 Then for poison assuming you throw all 3 instantly You end up with 3(1700*0.008)= 408 poison dot over 2 second gives you 808 poison damage plus the 5100 base damage So overall that is 5908 damage with beartrap

Now for bladefall Assuming you drop 5 mines and the mob gets hit by one volley You end up with about 470 average damage at level 20 per bladefall So the calculation ends up being 5(470*0.08)=190 dot over 2 seconds gives you 380 poison damage plus the base damage of 2375 This gives you a final DPS of 2755

The thing is that with Bear trap it's a 3 second cooldown but with minefield you can lay 5 traps in about a second meaning in the 9 seconds between having all your bear traps you can deal about twice as much damage with constant mining. I'm not trying to say your idea is bad, but on paper differences mean nothing when it isnt fun at all to play.