Colorless artifact prison deck powered by Mishra's Workshops. Built as a pure artist proof only deck (signed by the artist on front with clean/unmarked white backs) and played in Dragon Shield clear sleeves. Considering that the foil and Masterpiece proofs were limited to 30 pieces, statistically speaking, its possible for another 6 such decks to exist. Tho actually acquiring these proofs will prove insanely challenging, as this deck took many years and much effort to complete and maintain (modernizing with new cards or print variants). Not all artists will respond, and some artists won't respond to any form of contact no matter how much you offer (Chippy for Precursor Golem for example). In some cases, I prodded the artist once a month for many months before a response was received.
WotC will forward your mail to an artist: Artist Name/Artist, C/O Wizards of the Coast, PO Box 707, Renton, WA 98057-0707
Not all artists will publish their email on their website or even provide a contact form, but you can still email them thru a a domain who-is service: https://whois.icann.org/en
It's also challenging to convince the artist to leave the backs unmarked, since some artist will stack your cards immediately after signing, probably out of habit. I'd say 1/3 of the time an artist will stack your cards immediately after signing and ship them stacked, regardless of having received a request to penny sleeve each after signing, a request made in writing by email, by picture attachment, and by video URL. Some will exchange, otherwise your SOL.
Please contact me if you have any of the following APs available for sale or trade: http://www.neo-geo.com/magic/artist-proofs.html