I was thinking this:

+ Mini crits from behind
+ Leaves tracer of fire, lasts for 1.8 seconds then fades away (Tracer sets enimies on fire if they walk through it, the tracer stretches about three flame thrower flame widths)
+ Alt+Fire: Shoots head consuming 5 bullets (Small knockback and lights enemys on fire, takes 4 seconds to reload head))
- (While equiped) Mini-crits whenever it would crit and shortly after unequiped
- Minus 20% clip size
- 10% slower reload speed
- No random crits


Item set:
Backburner
Calefactor
Back Scratcher
Hottie's Hoodie

Item set bonus:
+ 5% Chance to scare player with melee equiped (for 2.2 seconds)
+ Minicrits players that have dominated you (Until you get a revenge)
- 10% slower walk speed