[Orochi]

From what I've seen, he offer's little more than what regular Engineers offer. I personally would rather put my faith in a Grey seer when it comes down to casting, and have a couple of Warlocks running about with all the fancy gadgets.

For 400 points, skaven characters aren't exactly difficult to take down, So you'd need to keep him well protected.

 

[Orochi]

Yes but for what will be coming after him, that isn't really enough as a stand-alone. Hence why you need to keep him protected.

Other reasons I posted as not to take him still stand.