greatskull and runemaw: would this work??

ok i recently had an idea to hurt enemy magic missile armies (hello tzeentch), and have discussed it with a few other gamers and right now am split on whether i can or can not do it.

so here goes:

XXXXXXXXXX              OOOO                     YYYY
(gnoblars)       (IG +tyrant/runemaw)    (Ogres+butcher w greatskull)

1 -so the enemy casts sees that im charging up with my IG's + tyrant ready to lay the hurt on and says "i better magic him to death",
2- casts magic missle at juciest target (tyrant and IG)
now if he rolls double 1,2,3's i redirect onto butcher with greatskull causing a miscast
if he succeeds i redirect to gnoblars

would he have to roll on the miscast if I redirect on to the greatskull butcher????

would he have to roll on the miscast if I redirect on to the greatskull butcher????

No, because Butchers can't take a Greatskull in the first place.

However, say it was a Bruiser instead of a Butcher, I don't think he would suffer the miscasts.
The rules for Greatskull says that any spell targeted at the unit suffers a misscast on double 1/2/3.
He does not target the unit with Greatskull, it's that redirected to the unit.
The spell is targeted and cast on the Tyrants unit, the powerdice rolls stand and are done before you redirect, and there's still a chance that it won't redirect at all.

Thats how I would play it, wheter I would play Ogres or not.

This has come up - maybe it was even FAQ'd.  Minsc is correct, for the Greatskull to work your unit needs to be targeted. 

This doesn't stop you from taking the Greatskull on your Tyrant, and if they don't miscast re-direct onto your gnoblars with Runemaw banner.  Yearrhgh!

ok thanks for the replies guys
too bad that it didnt work the way i had hoped

You could take some thiefstones instead of the greatskulls though, since they would benefit from the Magic Resistance, even though they wouldn't benefit from the greatskull.

(so thiefstones + runemaw)