Ach! Misinformation alert!
To start with, mind blast is pure physical damage. To add to that, mdr or pdr won't lower the damage dealt below zero - i.e. they'll take no damage, but you can't heal from pdr, only absorb.
IMO, at level 30 fire trappers are infinitely better than lightning trappers. MDR works at 1/5 effectiveness vs WoF, plus you have similar damage with fire traps, and much better stunlocking. The downside is of course that people willing to bm will slap on hotspurs, which you can't do (in lld anyway) vs lightning damage.
As far as skills go; for decent trap-laying speed BoS is a necessity, and you can't put enough into fade for its %DR to be noticable, and you can make up resistances elsewhere. Aside from that, the build's pretty simple. 1 BoS, 1 mindblast, 19 WoF (can't quite max it at level 30), and the rest - 17 - into fireblast. If you're going lightning, light sent gets 7 points with the rest into synergies, not surprisingly. You're looking at (with the gear below) 313average vs 528 average, but keep in mind it's easier to hit with fire, it hits a lot faster (three times the speed), and MDR works at 1/5 the effectiveness.
The gear;
Spirit longsword (longsword for speed)
Vipermagi
2 traps, res, fcr, stats, 2-socket etc. circlet*
2 traps etc (same as circlet minus sockets) amulet*
Magefists
Dual SoJs
Caster belt* (you're after FHR, stats and replenish life as additional mods to FCR)
Rhyme grim shield
*You'll need 17-27 fcr from these together, depending on how good your spirit is.
Gets you 10 frame trap-laying and casting with this setup. Chuck out 1 or 2 shaels depending on your belt (1 shael if it has 24 fhr), and use 1 or 2 fhr sc's to get to 5 frames. Keep in mind you can get 20%fhr or 34 life from a socket, and 5% fhr or 15 life from a charm.
I'm sure you know the stats already.