! this build need Zenurik Inner Might rank 5 or 6, and will be far less good without !

(If you do an heavy attack while sliding, you will not be totally immobile during it.)
The dagger have the fastest wind-up, and the heavy attack have a guaranteed slash proc, that ignore armor to easily kill greener even in steel path.
The principle of build is to stack Combo Counter, and do Heavy attack with an high multiplier, that will use 10% of this combo, to kill the ennemis with this slash proc.
(it don't need to be at max combo to kill the steel path greener in 1 heavy attack.)

the other build, with only heavy attack :
https://overframe.gg/build/61444/karyst-prime/full-heavy-attack-slash-viral-karyst-prime-build-for-easy-steel-path/
(less damage, don't need to alternate between normal and heavy attack, don't need Inner Might)

the goal is to have 90% (the maximum) of combo efficiency with [Focus Energy] + Inner Might, to only spend 10% of the combo at each heavy attack.
(not use Inner Might would mean to use also [Reflex Coil], or a riven with combo efficiency ; instead of [Drifting Contact], with something other to keep the combo.)

Use the 2 melee arcane ([Fury] and Strike) will make the build mush more efficient.
Arcane Strike is near indispensable and make us 60% faster ; Arcane [Fury] will increase the damage of 60%.

The [Life Strike] will heal all HP at each heavy attack, making you near immortal. Especially with [Adaptation] and more health. (this make the energy shield near useless)
Even at rank 0, it will heal all in most case.

The corrosive is good to kill ennemis with armor, because it ignore 75% of the ferrite armor and make 75% more damage to it, so it make near 7 time more damage to the greener of the steal path ; but they have so mush armor the even this is not enough. So we rely on the slash proc, that ignore 100% of the armor ; and the corrosif is just a small bonus.

The [Reach] is not optional, increase the range make this weapon much more pleasant to play, and make possible to kill a lot of ennemis in one hit.
The dagger have the highest (0.9) [Follow Through] of all melee weapon (except exalted), making the damage penalty after hinting lot of weapon in 1 hit very low. as exemple, the 5th ennemis take 66% of the damage of the first target. for a sword, that have a [Follow Through] of 0.7 (average for the melee), it would only be 24%.

If you don't need the combo duration (as exemple, because you use the aura [Swift Momentum]), [Primed Smite Grineer] or Quiquering are probably the best choice.

Why not use Condition Overload, on this weapon that apply 3 status on the heavy attaque and have 30% status chance : because the goal is to one-shot. [Condition Overload] is very strong, but need to already have apply status to have bonus damage.

For a riven, the best stat to have are (in decreasing order) :
-combo efficiency (at least 30, to put the riven instead of Focus Energy)
-range
-cold damage (to create viral. use Reflex Coil instead of Focus Energy to not make magnetic)
-combo duration (to put the riven instead of Drifting contact)
-attack speed
-damage to Grineer (because with slash proc, it is take 2 time in the damage calculation, making it very effective)
-crit damage
-crit chance
-melee damage
IPS and elemental damage other than cold are near useless ; we don't use initial combo ; the other faction damage are not really useful because if we can kill a greener, we can easily kill anything other. have a negative slash damage is not a problem at all, it don't affect the dommage of the slash status.