Kraxton's 'Super Krak Grenade' Focus Invis
 Veteran Build - Warhammer 40k: Darktide 

A build meant to mirror the Frag Grenade variant on Canary, as Lethal Proximity DOES effect Krak's too...not by a lot, but you can get more 'double kills' with them with the crusher hordes not as scrunched up, so I still felt it worth throwing it together.

With Krak's being so much more situational though than frag's, I went with a 'maximum damage!' build to really see them shine. I omitted Demo Team since getting Krak's shoved into you isn't nearly as important as Frags, same reason as for not taking Field Improvisation. And with the Extra free point from not needing the range pip for Frags as well, I was able to take Invis, to take advantage of the 'Surprise Attack' damage bonus, on top of getting that extra Grenadier grenade. and with the last extra point, I throw it into Focus Target, as it will help you see big chunks taken out of Monstrosities that much more. I ignore Rending Strikes too, as I noticed it didn't really help Krak's as I think they have 100% rending/their own modifier for all types of armor, so the extra rending didn't really do anything for them.

But yeah, other than that, just bonk with the Chain Axe, keep yourself topped off with out for blood, and throw a Krak here and there just for fun. Nuke lots of armor, drop monstrosities with Krak's alone, and have a good time with your explosive hand gun.