Here is a very simplistic build that pretty much takes everything (so you can try everything) and slots it in a generic but passable way. You could do so much more than this of course, but this would get you started.
I'm not saying its the best, its just a functional example.
Lewis
Villain Plan by Mids' Villain Designer 1.401
http://www.cohplanner.com/
[u]Click this DataLink to open the build![u]
Level 50 Technology Mastermind
Primary Power Set: Mercenaries
Secondary Power Set: Traps
Power Pool: Flight
Power Pool: Fitness
Ancillary Pool: Mace Mastery
Villain Profile:
Level 1: Soldiers -- Acc-I(A), Acc-I(3), Dmg-I(3), Dmg-I(5), Dmg-I(5), EndRdx-I(33)
Level 1: Web Grenade -- Acc-I(A)
Level 2: Caltrops -- Slow-I(A), Slow-I(46)
Level 4: Triage Beacon -- Heal-I(A), Heal-I(7), RechRdx-I(7), RechRdx-I(34)
Level 6: Equip Mercenary -- EndRdx-I(A)
Level 8: Hover -- Flight-I(A), Flight-I(9), Flight-I(9)
Level 10: Acid Mortar -- Acc-I(A), Acc-I(11), RechRdx-I(11), RechRdx-I(23), DefDeb-I(43), EndRdx-I(46)
Level 12: Spec Ops -- Acc-I(A), Acc-I(13), Dmg-I(13), Dmg-I(15), Dmg-I(15), EndRdx-I(33)
Level 14: Fly -- Flight-I(A), Flight-I(19), Flight-I(19)
Level 16: Force Field Generator -- DefBuff-I(A), DefBuff-I(17), DefBuff-I(17)
Level 18: Swift -- Flight-I(A)
Level 20: Poison Trap -- Hold-I(A), Hold-I(21), RechRdx-I(21), RechRdx-I(23), RechRdx-I(37)
Level 22: Health -- Heal-I(A)
Level 24: Stamina -- EndMod-I(A), EndMod-I(25), EndMod-I(25)
Level 26: Commando -- Acc-I(A), Acc-I(27), Dmg-I(27), Dmg-I(29), Dmg-I(29), EndRdx-I(33)
Level 28: Seeker Drones -- Acc-I(A), Acc-I(31), Dsrnt-I(31), Dsrnt-I(34), RechRdx-I(34), RechRdx-I(40)
Level 30: Serum -- RechRdx-I(A), RechRdx-I(31), ResDam-I(43), ResDam-I(46)
Level 32: Tactical Upgrade -- EndRdx-I(A)
Level 35: Trip Mine -- Acc-I(A), Dmg-I(36), Dmg-I(36), Dmg-I(36), EndRdx-I(37), RechRdx-I(37)
Level 38: Detonator -- Acc-I(A), Dmg-I(39), Dmg-I(39), Dmg-I(39), RechRdx-I(40), RechRdx-I(40)
Level 41: Web Envelope -- Acc-I(A), Acc-I(42), Immob-I(42), RechRdx-I(42), EndRdx-I(43)
Level 44: Scorpion Shield -- EndRdx-I(A), DefBuff-I(45), DefBuff-I(45), DefBuff-I(45)
Level 47: Web Cocoon -- Acc-I(A), Acc-I(48), Hold-I(48), Hold-I(48), RechRdx-I(50), EndRdx-I(50)
Level 49: Power Boost -- RechRdx-I(A), RechRdx-I(50)
------------
Level 1: Brawl -- Acc-I(A)
Level 1: Sprint -- EndRdx-I(A)
Level 2: Rest -- RechRdx-I(A)
Level 1: Supremacy
<font class="small">Code:[/color]<hr /><pre>| Copy & Paste this data into Mids' Hero Designer to view the build |
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Random AT Generation!
"I remember... the Alamo." -- Pee-wee Herman
"Oh don't worry. I always leave things to the last moment." -- The Doctor
"Telescopes are time machines." -- Carl Sagan
Couple of questions
1.) What do you think about Serum?
2.) Does PowerBoost boost defense of FFG?
"Yes, winning all the time can be boring."
-Knight_Chill
"It's amazing how well you can put up with endurance issues if you hide them under a large enough pile of bodies."
-Spiritchaser speaking on Dom Revamp
[ QUOTE ]
1.) What do you think about Serum?
[/ QUOTE ]
I dont know, because my Merc/Storm never took it and neither did my Merc/Dark. I simply included it in the build because I figured he might want a build that let him try every power. Then he could respec out of any powers he (original poster) doesnt like.
[ QUOTE ]
2.) Does PowerBoost boost defense of FFG?
[/ QUOTE ]
I have no idea, since I have never had Black Scorpion in conjunction with either Traps or Force Field. Again, I just included almost all the powers I could, and it so happens that I really dig the Black Scorpion powers. I threw Power Boost in there more because if you only have 1 extra slot left at level 50, Power Boost is a decent one to have if you will only have a total of 2 slots to put in the power.
Honestly, I should have stated up front that I have never played the combination that the OP asked about. I have tried the primary and the secondary to high levels, but not together, and I've never played /traps with Black Scorpion.
Still, I've played enough Masterminds that I was hoping I could still be helpful, since the question seemed to be a request for a basic build. I think the build layout looks serviceable based on experience with the power sets in different combinations.
Since I'm not a master Mercs/Traps player though, I'd be more than happy for someone else to come in and correct me / scold me / help the OP. 
Lewis
Random AT Generation!
"I remember... the Alamo." -- Pee-wee Herman
"Oh don't worry. I always leave things to the last moment." -- The Doctor
"Telescopes are time machines." -- Carl Sagan
I don't think powerboost will work on the FFG. My guts says +special doesn't transfer to things you summon, but I could be wrong.
[ QUOTE ]
Couple of questions
1.) What do you think about Serum?
2.) Does PowerBoost boost defense of FFG?
[/ QUOTE ]
1. Serum is very skippable. I took it the first time and then respec it out. The "god-mode" doesn't include psionic resistance and that's sad because a lot of times the team may need psionic resistance to take alpha. The endurance crash is kinda annoying too. And the duration is only 60s. You can easily skip this power and save some purple/orange for your Commando before the tough fight.
2. My gut says Power Boost does not transfer to FFG. FFG is not even a pseudo-pet. It is actually a real pet that can be target.
PS: Take Aid Other and 5-slot it. Your pets and teammates will love you.
What's left is to normalize all Assassin Strikes and improve Stalker's old sets (Claw, MA and EM)! You don't need to bring back the missing PbAoE attack. You just need to make the existing ones better! For example, make Slice a WIDER and LONGER cone.
More, new, and different MM/Traps Questions. Well, different for this thread at least.
I'm about to hit the 60 month mark, and that means some respeccing. I have a Merc/Traps at 35 and I have some questions about some of the Procs and slotting. A note on IO's Unless they fall into my lap, they don't exist. My Alts to Inf ratio does not support the planned use of any IO sets.
Okay, so part of this respec was to drop Serum. I've gotten to 35 and used it like 4 times. Now, on with the questions.
Mercs- I read somewhere that it's not worth slotting for the heal because the Medic won't heal until he can use the full potential of it. Slotting for heals therefore makes him less likely to do it. Is this true?
Acid Mortar. I happened to get an Achilles' Heel -Resist Proc. Would this have any effect in Acid Mortar? How about in the
Mercs?
Best non-proc slotting for Acid Mortar and Poison Gas trap?
Seeker Drones? Yea or nay? If so, what slotting?
My first short story (detective fiction) came out in Jan-2012. Other stories and books to follow, I hope. Because of "real writing". COH was a big part of that happening.
Here's a different take on Serum: I like it a lot for PvE. I have a Mercs/Pain MM in the 40's, with Serum 4-slotted (three rchg, 1 res). I'm running mission arcs on Challenge Level 3 or 4, and find Serum makes a HUGE difference in my ability to put down EB's @ the end of my missions... toss it to the Commando right before fight and let him take the alpha. He generally holds aggro for the remainder of the fight, and that's a ton of heals I don't need to throw, which also means a lot more attacks I can add to the mix.
Yes, there's a -end crash, but:
(1) If you're talking about tossing him purples/oranges instead of Serum, well, 1 blue ain't no thing then, is it?
(2) Painbringer pretty much makes that a non-issue for the /Pain build
Other than EBs, do I pop Serum often? No, not really. Not sure what I'd take in its place for more overall utility, though. Definitely not M-30. :-)
The Achilles' proc does indeed work in Acid Mortar, as well as the mercs. If you only have one, I'd slot it in your Soldiers since that gives the most chances for it to fire. Though really, Mercs / Traps needs several of those procs so you may want to save some merits or tickets to try to get more.
I'd slot Acid Mortar and Poison Gas Trap with 3 recharge each. I'd also give Acid Mortar a couple of defense debuff and an accuracy. Poison Gas Trap can use a hold enhancement or two, but it's not critical... the -regen is the biggest reason to get it after the nerf.
Seeker Drones are great at soaking up alpha strikes. Slot them with some recharge and maybe a bit of range and summon them right on top of a group of enemies from outside aggro range. The enemies attack the drones, the drones go boom and debuff the enemy damage, and your pets open fire. Add an accuracy if you care about the debuff landing and have a spare slot.
Oh... you may want to check the market before writing off IO sets altogether. If you ignore set bonuses and just concentrate on enhancement value and cost (frankenslotting) you can actually slot most powers with set IOs for about the same price as level 35 generic IOs, which is actually cheaper than buying SOs at 35, 40, 45, and 50. There are plenty of recipes to be had for a few thousand to a few tens of thousand inf, and as long as you avoid ones with expensive rare salvage you can buy the salvage and craft for under 100k. I can almost always frankenslot a character in the low to mid 30s for less inf than I earn just running missions and selling drops on the market. No marketeering or loans from rich alts needed... just sell any salvage you get and any recipes with a demand and you should have a few million by the 30s. Or a few hundred million, if you do a lot of SFs and get some lucky merit rolls. 
Cascade, level 50 Blaster (NRG/NRG since before it was cool)
Mechmeister, level 50 Bots / Traps MM
FAR too many non-50 alts to name
[u]Arcs[u]
The Scavenger Hunt: 187076
The Instant Lair Delivery Service: 206636
I was wondering if anyone whould post a merc/traps build becuase i cant seem to find one.