Don't make one.. Instead I would suggest Merc Traps.. As for the build just copy a Robot Traps build and replace with mercs.
Look a bit lower you will see someone revived Rattero thread which I think has a excellent Traps build for any mastermind.
1. Why Soft Cap is Important : http://dechskaison.blogspot.com/2011...important.html
2. Limits: http://paragonwiki.com/wiki/Limits
3. Attack Mechanics: http://wiki.cohtitan.com/wiki/Attack_Mechanics
4. Rule of Five: http://wiki.cohtitan.com/wiki/Rule_o...e_Law_of_Fives
why traps over ff?
Need build ideas for a Merc/FF MM, no purps or uber builds, for farming..