Myphetic Blight Haulers and abilities that ignore cover

[Vorenus]

Greetings from the Eye:

 

Myphetic Blight Haulers grant all Death Guard units within 7" the benefits of cover.  How does that work against units that have a special rule that ignores cover, such as, for example, the Iron Warriors?  Do the two special rules negate each other?  Does one take precedence over the other?  If they negate each other, does that mean that units actually in terrain would gain the benefits of cover (which they wouldn't if they were hit by something that ignores cover, but maybe the Myphetic ability cancels the "ignores cover" and so maybe it works that way?)?

 

Thanks.

 

--Vorenus

[BrainFireBob]

It gives them cover. Then that cover is ignored