The Duracell Warlock - Lightning Battery Build
 Psyker Build - Warhammer 40k: Darktide 

Classic Lightning Staff Battery build, not OP but "a nostalgic weapon from a more civilized age"

A cylindrical device of base metal and stored charge, the runes upon its casing long since worn away save for a single surviving glyph: "AA." The Adeptus Mechanicus, in its infinite and occasionally misguided reverence, has bound this relic to a Psyker for testing. 

• Electrokinetic Force Staff - Your Duracharge, It is good at most things great at nothing, high Warp Siphon is necessary for decent breakpoints with secondary attacks for gunners and ragers and armor etc. Kinetic Flayer plays surprisingly well with it as when aiming at groups the secondary lighting attack often travels onto the next target rather then wasting the charge. could do Smite but the staff provides solid CC already with the stuns from secondary. I find a full change unnecessary unless into bosses and crushers, so do half spams into most threats and to get Warp Flurry up quicker. 
• Warp Siphon - Keep it topped up, because the breakpoints need the juice. Inner Tranquility ,Battle Meditation and Empyric Resolve means you can have crazy uptime with the staff and can hover around 80 to 90 peril for maximum punch. 
• Vent - only as an emergency or utility, No investment here as your basically draining the battery early, and the whole point of this thing is that it's supposed to run until it's actually spent, not before. Honestly this build is a commentary anti synergistic nature of Warp Siphon.  
• IIIisi Sword -  for when your duracharge needs a rest or your sitting at 100% peril. A great backup for horde and maniac, light attacks answer most threats, the special providing cleave where needed, Deflector is good through i admit, it is easier to remember to duck behind cover than to remember what runes were inscribed upon one's own kit that morning.