Fitz's H40 Optimized Vet - Mr. Fundamentals
 Veteran Build - Warhammer 40k: Darktide 

Shout is still insane value and rez shout should be normalized as being standard now. If you have two veterans, this becomes even stronger, but one can run Weapon Specialist instead. If you're somehow not into VoC revive then put that point elsewhere.

From my testing, both Rending Strikes and Onslaught perform about the same into H40 Crushers with full Skirmisher stacks, Agile Engagement, and Focus Target, comfortably above the 1 combo breakpoint. Where Onslaught will perform better, however, will be into monstrosities where that brittleness is allowed to stack further. 40% used to be very low compared to things like Uncanny and Armourbane, but these have since been nerfed back into line, so Onslaught is equivalent to Uncanny but in your tree. As for the aura, I think Survivalist will still greatly impact your team despite its 50% nerf.

If you want a more generalist/hybrid style instead of primarily melee, swap the 15% damage node for Duck n' Dive.

Blitzes are case-by-case, if the map has armor (krak), melee packs of ragers, vanguards and bruisers (shredders), or mostly gunners (smoke).