Lear more about the Knell Prime : https://warframe.fandom.com/wiki/Knell_Prime

--> Landing a successful Headshot grants the "Death [Knell]" buff, additively increasing the modded critical multiplier by 0.5x and modded status chance by 20% and stacks up to 3 times, and also increases Ammo Efficiency by 100%. The buff lasts 2 seconds and can be refreshed on subsequent Headshots
--> Death [Knell] adds a flat Critical Multiplier by 0.5x and a flat status chance by 20%. It also grants unlimited ammo. The buff lasts for 2 seconds and can be refreshed.
--> Critical Multiplier and Status Chance bonus can stack up to 3 times. When the buff times out, one stack is lost and the buff duration resets.

About this build :

• The Riven displayed is my own one.
• The malus totally removes the Puncture stat, leaving only Viral, Impact and Slash.
• The idea is to convert the remaining Impact stat into Slash via Hemorrhage.
• As "Death Knell" can only be maintained via headshots, Galvanized Crosshairs and Secondary Deadhead are mandatory.
• I recommend using Arcane Velocity : a very high fire rate value takes full profit from the Death Knell mechanism.
• Can be equipped on any warframe, synergizes well with Gloom as the ability helps aiming for the head of enemies by slowing down their animation speed.
• Easily melts the most tenacious of enemies : it will melt anything from the start. However once the Arcane and Galvanized mods are activated, everything evaporates.
• [Hornet Strike] and [Primed Target Cracker] provide damage to the bleed effect.

Without [Hemorrhage] :

(average value 57 slash procs)

With [Hemorrhage] :

(average value 112 slash procs)