These need to be talked about, are being argued about on the forums, and FAQ'd as soon as possible because the wording of how they work is so poor and confusing. I will fully admit to making exactly the same mistake that it seems a lot of people are making the first time I read it, and I just know that it is going to lead to a lot of arguments as soon as they end up on the tables. Its all down to the description of how they wound.
The exact description in the Codex (and this goes for Imotekh the Stormlord's Staff of the Destroyer) is:
"Every Unit underneath the line suffers a number of hits equal to the number of models in the unit underneath the line."
Now the broken interpretation is that every model in any unit with 1 or more models under the line is hit, this is how I first read it. Imagine, a unit of 30 Boyz with a single model under the line takes 30 S10 AP1 hits, crazy!
I pretty quickly realised on re-reading it that each unit with models under the line, takes a number of hits equal to the number of models under the line, and the wording therefore lets the owning player distribute the hits as they see fit (just like shooting). So in the above example, the unit only takes 1 S10 AP1 hit.
Now it may seem pretty obvious to a lot of people, but who out there really doesn't think that someone is going to try and argue the first interpretation, and I've even heard it being interpreted that way on podcasts.
Whats all your thoughts?