Not yet, no rares. Pets are now just becoming tameable.
Its actually pretty simple. DoT is applied to all targets in 5-8yd range upon trap tigger. Trap explodes, deals direct damage, applies DoT. There is no ground part. You do bring up a good point with the pre-trapping(as thats the point of a trap). I couldn't see it being a hybrid between current ExT and my idea though, would have to be either ground AoE or multi-DoT AoE. I wouldn't be concerned with LnL proccing later, as on live, in AoE situations, most SV hunters dont use ExT until all mobs are in one location(and this usually doesn't take too long). I'd imagine with Shadow Trap, it would work the same. Normal AoE/single target until tank has mobs together, launch Shadow Trap, trap is triggered and DoT spreads, profit.