-Was able to snag a 57% Elec from the old man from Perrin but I never really bothered Valence fusing to 60%. You can use any Progenitor.
-Use [Primed Pressure Point] if you want. There's really no point for the extra crit if you're not reaching the next tier with Sac Steel unless it's a sustained DPS light attack build. I just want that extra damage to Sentients.
-Use [Primed Fury] if [Berserker Fury] isn't really your thing but getting 2 kills right away is easy with heavy attacks and is easy to maintain.

Last 2 Slot Options

Riven- If you have one. For Heavy attacks Spam CD IC DMG CC Harmless Neg. If you want it to be also useable on light attack builds CC CD AS Harmless Neg

Faction Mod- Players generally dislike faction mods but this will be my first option to slot in for the double dipping of Slash Procs.

Primed Fever Strike- Highest upfront increase in damage if you already slotted a Primed Faction Mod. My 2nd option.

90% Elemental- Only use together with [Primed Fever Strike] IF you did not use a Primed Faction Mod. Why? Because you can make Viral, Gas and Corrosive and take advantage of some enemies that take bonus damage from those said elemental combos unless you're going pure Toxin then screw the idea and use something else.

Gladiator Might- +CD Scales really well for your forced slash procs but this is better used for hybrid 12x Heavy attack build. With that being said this is still the best option to combine with [Primed Fever Strike] if you forego Faction Mods for double dipping slash and it gives higher upfront damage than a Faction Mod.

Primed Reach- Great in general especially if you don't have grouping up abilities and in Non-endless missions like Exterminate.

Dispatch Overdrive- 60% Movement Speed on Heavy Attack hit. Easy to maintain. Nice for Non-endless missions.

Life Strike- One of the few existing Life Steal mods in Warframe. 20% Life Steal on Heavy Attacks.

Quickening- 40% More Attack Speed