I’ll give it a whirl, the slow effect helix always had me curious but I never bothered trying it. A few things that caught my eye:
The 4th hit slows helix applies to his secondary attack? I had always assumed it only applied to his main attack. I suppose it does just say “melee hits”. On that note, the ground pound comes out as 2 pounds per secondary fire, have you checked to see if this means the slow happens on the second fire, or does it have to be four fires?
I’m wondering if Quick Bite might be a better choice over Diffusion on level 2 for this build - helps you keep the slow applied to multiple targets by keeping your speed up so you can bounce between them faster.
Shield Penetration was just a random choice? Given that this build, like any other Kelvin build, uses Chomp constantly, I think a +shield max gear would not be out of place at all.
Back when I was first figuring Kelvin out, I did pick the Slow mutation a lot until I figured out how useful the stun was for setting up Chomp finishers, so I definitely know the sort of movement you should be doing to maximize the Slow field.