If you use an external source of Viral (panzer) and want to focus on alt-fire, drop Rime rounds and Malignant force (due to abysmal status chance of alt-fire) and slot [Vile Acceleration] and [Bladed Rounds], and replace [Point Strike] with [Critical Delay].

Ideal riven : +CC, +CD, +fire rate

For Corpus: Drop [Hunter Munitions] and [Rime Rounds] for [Infected Clip] and [Primed Shred] or [Vile Acceleration]. You can also swap Point strike for Critical Delay if you have +fire rate.
For Infested: Drop Hunter munitions and Rime Rounds for Shocking touch/High voltage and Primed Shred/[Vile Acceleration]