My own necro/traps is quite young (only level 21 so far), so I can give only some suggestions.
First, slot your Lich for -to hit debuffs; the defense totals for your minions that you can set up, even with the 2 defense procs and maneuvers, won't be near the defense softcap. You'll need to hit debuffs to make your pets durable for longer fights against tough opponents. Second, even if you slot the Lich for to hit debuffs you'll probably have some degree of difficulty with EBs, AVs, and GMs that have PbAOEs (and to a lesser degree anything else that resists to hit debuffs). Zenflower, Woodsman, and a few other predictably difficult Heroes / AVs for MMs will still be difficult for you.
Third, seeker drones are a *really* valuable addition to your arsenal, as a necro/traps. You can reduce incoming damage more than the listed 40% by using seekers (when mobs are mezzed and the seekers' "to hit" debuffs cause mobs to whiff). Slot them up for accuracy, recharge, and to hit debuffs to get the most out of them.
Finally, everything other than "big fish" who are known for being difficult for MMs will probably be fodder. And, you'll get more use out of detonator than any other kind of /traps MM can. Making the Lich go "boom" and then using Soul Extraction should be good fun, and very effective. 
Hopefully these random thoughts prove helpful.
I've got a level 50 Necro/Traps its a great combo really.
ShoeTattoo touched on the main synergies with this, but I have to disagree with his opinion on Seekers. The mag stun is low and cannot be relied upon fully, the debuff is still nice however. I have detonate but, only find myself using it on large teams. I've used it in the past to detonate my lich so I could use the extraction for an AV fight.
I didn't bother with maneuvers and found with the lich slotted for -tohit I do alright. As far as AV fights go, make a mine field before the fight and lure them through.
i played with this set in mids and am thinking i might do well frankenslotting for recharge and trying to pump out zombie bombs and other thing that go boom at the fastest rate possible. Think it'll work?
I went ahead and jumped into Mids. I'll forewarn you, I've not played too much with necromancy and I have done tons with traps, so some of this build is pure guestimation. That said, this should be at least better than average for what you want to do.
Soul extraction is down to almost 300 seconds, and detonator recharges faster than that, so you should be pretty close to perma on the ability to keep that up and running. Just remember the endurance drain is going to be ridiculous if you intend to keep a wraith out along with fully upgraded pets all the time, but the possibility is there.
You've got softcapped S/L defenses, about 30% positional, and triage becon to keep you alive. Provoke because you can probably tank better than your minions on hard targets. This build is meant to be in melee taking hits for your zombies, jump in, poison trap, web envelope, trip mine, and things will start dying pretty quickly. The lack of softcap means that toebombing is going to be frustrating to try. Trip mine fields are highly recommended, I know on my bots/traps I sometimes let the bots take aggro for a while while I build a field, then taunt and run behind a corner to pull bosses through four or five mines.
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I'm working on a Necro Traps and am having a lot of fun with it, but im not finding any info on the combo and very little on traps itself. Can anyone help me out, some thoughts, tactics, links, anything about this combo you can tell me? Please help me smooth my ascension to the rank of Zombie Bomber. "Making Corpses Go Boom" would be an awesome name for a guide.