I have to say that all three of Avati's genre pictures rank amongst my all-time favourite Italian horror films. HOUSE is top of the pile, but I find both ZEDER and L'ARCANO INCANTATORE fascinating; beautifully directed and photographed, with a unique atmosphere of conpsiracy and paranoia mixed up with a certain quaintness and an attractively rural Italian feel. It's interesting that SHORT NIGHT OF THE GLASS DOLLS has also been mentioned, as that's another of my favourites, for many of the same reasons.
I posted a review of HOUSE on MHVF some time ago, it's now available
here and gives a better breakdown of just why I like it so much. I also reviewed ZEDER, and that review can be found
here. I keep meaning to write a review of INCANTATORE but I can't face watching any of my three(!) dire bootleg copies again, and keep thinking surely it must be released on DVD soon...
I also have a copy of Avati's borderline genre film CHILDHOOD FRIEND, which is only really recommended to serious Avati fans, and the weird, litte-seen Avati-produced HOUSE remake, 'La Stanza Accanto', directed by Fabrizio Laurenti.