Always aim. Always aim for the head.

[Wildfire] increases clip capacity, reducing loss of sustained DPS from long reload time.

Replace Primed Bane with [Vigilante Armaments] for general use. [Stormbringer] (and reordering) will yield slightly "higher" damage, but give you Viral+Radiation and lose the armor reducing benefits of Heat.

• Don't bother with crit. If you had a Riven with +316.5% crit chance, you would still have less than a 4.2% chance.
• Don't bother with more status. You'll be trading substantial damage for a tiny chance to add another proc. It will not balance out and weaken the weapon overall.
• Don't bother with Fire Rate mods like [Vile Acceleration] or [Primed Shred]. You'll weaken each shot, burn through the tiny (45) ammo pool, and hit the long (2.7 second) reload far more often. This is a status sniper, not a mediocre spray n' pray.
• You don't want Punch Through. It will negate the weapon's AoE by detonating harmlessly in the background.
• The AoE range is small (1.7m) so [Primed Firestorm] doesn't give you huge amounts of extra range. It's still going to be the next door neighbor and not the whole neighborhood.
• [Hunter Munitions] procs on crit, Internal Bleeding procs on Impact. This weapon does not do significant amounts of either.

For a Riven, you want +Damage and/or +Elemental damage and Status Chance*.

* This will push Status Chance to "Guaraunteed" (100%+) without lowering damage like 60/60 mods will.