The [Pyrana Prime] is easily amongst the strongest secondary weapons in the game, combining huge raw damage, status stats, crit stats and awesome firerate which, when boosted by the passive effect of the weapon, will be quite destructive on top of the extended clip (which can give you a free instant reload in theory). Also take note that, as a shotgun weapon, the [Pyrana] is EXTREMELY efficient at triggering headshots because of the bullet spread, making Harrow an excellent wielder and making some Arcanes extremely easier to proc.

This is a pretty standard mixed status/crit setup for secondary weapons, with the obligatory Hornet/Barrel Diffusion/[Lethal Torrent] along with crit boosters (who can easily be the rare variants instead of the primed ones, which will save you a forma) and damage/status hybrid mods. Using two of those is quite efficient to get a decent status chance without hurting too much base damage. If you don't have [Jolt], you can use the more common "[Frostbite]" to have the same damage, but change it from corrosive to viral. Some people will tell you viral is more efficient on fast-firing slash weapons, which is true, but the Pyrana is an exception to that rule because of its huge differences with most other secondary weapons :

1- Burst damage is better than consistent slash status damage, since you'll trigger the passive effect much more efficiently and faster

2- The strongest enemies in the game are the heavily armored Grineers, who have an HUGE resistance to base slash damage. Normally you bypass this by using fast firing light slash fire arms with lots of status, but because of the huge amount of projectiles shot by the [Pyrana], a single shot of corrosive can strip most of their armor, allowing you to oneshot them instantly the next shot. With slash procs, you would need to empty an entire magasine to stack enough slash damage to compare.

3-Viral is usefull mostly for single-targetting, since the status effect can't stack it's more efficient to cripple the enemies one by one with singe-target weapons, because going rampage on several enemies at once will have barely any effect since the status will probably run out while doing so and your slash procs will probably have an harder time finishing the job. With corrosive on a multi-hitting weapon such as the [Pyrana], you can safely strip the armor of several enemies at the same time without bothering focusing either of them. You can also proc SEVERAL corrosive status on a single enemy, which is devastating, while doing the same thing with Viral won't do any difference.

The two status types are the best for this setup, but corrosive is far more efficient and versatile, while also being strictly superior in the current meta. The problem with it is only "Jolt" being harder to get than the other hybrid damage/status mods.

[Augur Pact] is by far the least necessary mod of the bunch, so you can either personalise the build by replacing it with something else, but what I recommend is getting a Riven (which supports a surprisingly high disposition of 3/5, AKA 1.0) and putting it as a straight upgrade to the [Augur Pact]. Some people who are not used to firing slightly unstable weapons such as this will also probably like repalcing it by [Steady Hands], your choice