MBC

If u have ruin scard demon he replaces a diabolic tutor I find him fun

I like him too, but he's just so hard expensive to cast.   

Ik I used him in one of me other to pull reaver demon for field wipe

Yes. I can see the convinience of tutors, but I don't see them preferable to other overpowered cards. Yes, you could tutor for black sun zenith, or you could replace the tutor card with another copy of black sun zenith. Same chance of drawing the overpowered stuff you want

On the other hand, the tutor could be your 5th, 6th, 7th, or even 8th copy of your "overpowered" card, increasing your chances of drawing it.  The point is, yes you could tutor for Zenith, but you can tutor for any card you might need.  You can add one more of every card if you want, but that sort of defeats the purpose.  Heck, I've even used Diabolic Tutors to search for a badly needed land in some games.

But this is not my deck.