I has a lore question.
Nids make a shadow in the warp, effectively rendering warp related things null, ships can't jump, and all that right? Ork tech works half because of their belief functioning via the warp right?
Why does Ork tech work around Nids?
Because the Orks generate a shared gestalt psychic field themselves called the WAAAGH! that provides their physics-altering effects. They don't actually draw upon the Warp to do so, they make it themselves, which is why if enough Orks believe something (red things go faster), that effect happens. The effect's curtailed somewhat by the stupidity of Orks, but it's how an Ork that's having such a good time firing it's gun at someone that it forgets it ran out of ammo a while back can actually keep firing even with no bullets left. Their wierdboys use this field as a source of power instead of the Warp itself, which is why you don't really see any cases of possession or corruption amongst Orks. Since the Shadow in the Warp is essentially the static noise of Tyranid communications cutting off conventional access to the Warp, the Orks don't care since they don't use the Warp, they use the Waaagh!
Exactly. Of course, the Orks
do still use the Warp for FTL travel in space, so there is that. And it still has all the screwy effects it should; there's literally a certain Warboss in the lore that tried to go through the Warp for a WAAAGH!!, and wound up going back in time to the point before the WAAAGH!! was launched. The Warboss then decided he could kill his double in order to get two copies of his favorite gun, and he did, which also stopped the WAAAGH!! in its tracks.