[Primed Shred] is there to add penetration to the weapon, however I'm not a fan of the rate of fire it adds, I personally prefer playing with [Metal Auger].
My Riven can eventually be replaced by [Thermite Rounds] to combine with [Galvanized Aptitude] or you can also put [Critical Delay] to maximize the critical chances and reduce the rate of fire induced by [Primed Shred].
For the arcane, although this build is oriented in head shot I prefer to use the arcane Primary Merciless for the reduction of the time of reload and the increase of the ammunition max
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