If I mount my Old Blood on a Horned One (which does not suffer from stupidity) and place him in a unit of Cold One Cav is he now subject to Stupidity or are the Cold One Cav no longer subject to Stupidity? Second Question is about the Carnosaur Pendant - Old Blood in a unit has Carnosaur Pendant, causes a wound and is now frenzied. It is just the Old Blood that gains the frenzy right? Or magically does the whole unit gain frenzy? The first one I can see as the Old Blood is leading his troops on his Horned One and the other Cold-Ones just knee jerk reaction follow him wherever he goes and skip the stupidity roll. But the Frenzy thing I don't know, if it does in fact give the whole unit frenzy that seems a little cheeky.
To the first question: The oldblood on horned one would become stupid; in fact, if even one model in a unit is stupid, the whole unit has to take a Stupidity test. Also, the horned one would have to move at the movement of the cold ones, so there is absolutely no point in taking a horned one, unless its solo. To the second question: Only the oldblood gains frenzy. Hope that helps!